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Strange possible DNS problem with BT Home Hub



 
 
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  #1  
Old August 4th 14, 08:50 AM posted to uk.telecom.broadband
Mark Carver
external usenet poster
 
Posts: 458
Default Strange possible DNS problem with BT Home Hub

Strange problem this weekend.

A year ago, I set up extra wifi points for a friend who has a large
sprawling home.

She has a BT ADSL connection, with a Home Hub 3. That provides
a wireless signal in the main part of the house.

Last year, I extended the system. I used a pair of Netgear Powerline
adaptors, to provide an ethernet connection to the far end of the house,
fed from one of the LAN ports on the BT HH. At the far end
the ethernet output from the other adaptor, feeds a simple basic 4 port
ethernet hub. One feed from that feeding a TP Link TP-WR702N mini dongle
(configured as a WiFi access point), the other feed, feeding another TP
Link dongle, on the end of a 50 metre CAT 5 (in a separate building)

All has been working perfectly for a year. All three WiFi devices have
their own SSIDs, and I set the TP-Link dongles to Ch 1 and 13. I can't
remember whether I set the BT HH box to Ch 6, but there's no coverage
overlap anyway.

On Saturday, she phoned me to say there was no internet connection
available from either TP Link devices, but the HH WiFi was still fine.
The TP Links were giving a signal, just an 'empty' one. She tried
several devices, all the same. She'd rebooted everything etc.

I talked her through switching off WiFi on her laptop, and connecting it
via cable LAN to the four port hub. That worked fine, internet
connection available. So that confirmed the powerline chain, and the
little hub were OK. However still no luck with either TP Link device. At
one point attempting to connect via one TP link box, resulted in a BT,
'There seems to be a problem connecting to the internet' web page,
(presumably generated by the HH itself ?).

Yesterday, I set up a spare TP Link dongle I have to duplicate her
arrangement, so I could talk her through the checking DHCP and DNS
settings. She logged on to one of the TP link dongles, and all was in
order, it had been assigned a dynamic IP address by the HH, and it
itself had DHCP server disabled, so the IP address handout is managed by
the HH. It was showing the primary DNS server as the BT HH
(192.168.1.254) (Exactly how I'd configured it a year ago).

Then, we discovered, all was OK, internet connection available on both
devices. Very odd. It certainly wasn't 'finger trouble' on her part,
and the fault was originally detected by her daughter. The whole family
had been trying to make it work, by checking leads, and rebooting all of
Saturday afternoon before bothering me, and it was still the same
yesterday morning, before I rang back.

I can only think there was some sort of DNS problem, with the HH, or
within BT's network ? I don't thing the BT HH allows WAN side access
to remotely examine its parameters ? I might get her a 'proper' ADSL
router, so I can remote access in (she lives 100 miles away) but how
does BT Internet authentication work ?
Is it locked down like Sky's ?


--
Mark
Please replace invalid and invalid with gmx and net to reply.
  #2  
Old August 4th 14, 09:14 AM posted to uk.telecom.broadband
Andy Burns[_2_]
external usenet poster
 
Posts: 210
Default Strange possible DNS problem with BT Home Hub

Mark Carver wrote:

how does BT Internet authentication work ?


It just "knows" the subscriber number of the line it's connected to, no
username/password required.

  #3  
Old August 4th 14, 11:06 AM posted to uk.telecom.broadband
Roderick Stewart
external usenet poster
 
Posts: 561
Default Strange possible DNS problem with BT Home Hub

On Mon, 04 Aug 2014 08:50:40 +0100, Mark Carver
wrote:

Strange problem this weekend.

A year ago, I set up extra wifi points for a friend who has a large
sprawling home.

She has a BT ADSL connection, with a Home Hub 3. That provides
a wireless signal in the main part of the house.

Last year, I extended the system. I used a pair of Netgear Powerline
adaptors, to provide an ethernet connection to the far end of the house,
fed from one of the LAN ports on the BT HH. At the far end
the ethernet output from the other adaptor, feeds a simple basic 4 port
ethernet hub. One feed from that feeding a TP Link TP-WR702N mini dongle
(configured as a WiFi access point), the other feed, feeding another TP
Link dongle, on the end of a 50 metre CAT 5 (in a separate building)

All has been working perfectly for a year. All three WiFi devices have
their own SSIDs, and I set the TP-Link dongles to Ch 1 and 13. I can't
remember whether I set the BT HH box to Ch 6, but there's no coverage
overlap anyway.

On Saturday, she phoned me to say there was no internet connection
available from either TP Link devices, but the HH WiFi was still fine.
The TP Links were giving a signal, just an 'empty' one. She tried
several devices, all the same. She'd rebooted everything etc.

I talked her through switching off WiFi on her laptop, and connecting it
via cable LAN to the four port hub. That worked fine, internet
connection available. So that confirmed the powerline chain, and the
little hub were OK. However still no luck with either TP Link device. At
one point attempting to connect via one TP link box, resulted in a BT,
'There seems to be a problem connecting to the internet' web page,
(presumably generated by the HH itself ?).

Yesterday, I set up a spare TP Link dongle I have to duplicate her
arrangement, so I could talk her through the checking DHCP and DNS
settings. She logged on to one of the TP link dongles, and all was in
order, it had been assigned a dynamic IP address by the HH, and it
itself had DHCP server disabled, so the IP address handout is managed by
the HH. It was showing the primary DNS server as the BT HH
(192.168.1.254) (Exactly how I'd configured it a year ago).

Then, we discovered, all was OK, internet connection available on both
devices. Very odd. It certainly wasn't 'finger trouble' on her part,
and the fault was originally detected by her daughter. The whole family
had been trying to make it work, by checking leads, and rebooting all of
Saturday afternoon before bothering me, and it was still the same
yesterday morning, before I rang back.

I can only think there was some sort of DNS problem, with the HH, or
within BT's network ? I don't thing the BT HH allows WAN side access
to remotely examine its parameters ? I might get her a 'proper' ADSL
router, so I can remote access in (she lives 100 miles away) but how
does BT Internet authentication work ?
Is it locked down like Sky's ?


Is it possible to set static IP addresses for the access points
(dongles) themselves, while keeping DHCP for devices fed through them?

If network access was OK everywhere else before the access points, and
they were producing wireless signals but with no valid network
connection, then that suggests the problem is with the access points,
and I reckon a local IP address conflict would account for it, so it's
something to try.

Who knows how it happened (if that is what happened) but just to avoid
this possibility, I use static IP addresses on all my network devices
that are in fixed locations, and only use DHCP for portable devices
such as laptops and phones. Many routers are configured by default
with DHCP starting at a high number such as 64 or 100, so you can use
anything below that for fixed addressing, so you may not even need to
reconfigure the Home Hub.

Rod.
  #4  
Old August 4th 14, 11:18 AM posted to uk.telecom.broadband
Mark Carver
external usenet poster
 
Posts: 458
Default Strange possible DNS problem with BT Home Hub

On 04/08/2014 11:06, Roderick Stewart wrote:


Is it possible to set static IP addresses for the access points
(dongles) themselves, while keeping DHCP for devices fed through them?


Yes, it is. In fact I've done that on another 'remote' install of mine.

If network access was OK everywhere else before the access points, and
they were producing wireless signals but with no valid network
connection, then that suggests the problem is with the access points,
and I reckon a local IP address conflict would account for it, so it's
something to try.


Yes, that's possible, though the reboots that were attempted *should*
have flushed anything such as that out ?

Who knows how it happened (if that is what happened) but just to avoid
this possibility, I use static IP addresses on all my network devices
that are in fixed locations, and only use DHCP for portable devices
such as laptops and phones. Many routers are configured by default
with DHCP starting at a high number such as 64 or 100, so you can use
anything below that for fixed addressing, so you may not even need to
reconfigure the Home Hub.


Indeed, well worth a punt I think. I'm visiting in a couple of months,
so I'll do it then. If it fails again before then, I'll talk my friend
through the process remotely (she's getting very good at logging onto
http set up menus now !)



--
Mark
Please replace invalid and invalid with gmx and net to reply.
  #5  
Old August 4th 14, 11:30 AM posted to uk.telecom.broadband
Graham J[_2_]
external usenet poster
 
Posts: 723
Default Strange possible DNS problem with BT Home Hub

Mark Carver wrote:
Strange problem this weekend.

A year ago, I set up extra wifi points for a friend who has a large
sprawling home.

She has a BT ADSL connection, with a Home Hub 3. That provides
a wireless signal in the main part of the house.

Last year, I extended the system. I used a pair of Netgear Powerline
adaptors, to provide an ethernet connection to the far end of the house,
fed from one of the LAN ports on the BT HH. At the far end
the ethernet output from the other adaptor, feeds a simple basic 4 port
ethernet hub. One feed from that feeding a TP Link TP-WR702N mini dongle
(configured as a WiFi access point), the other feed, feeding another TP
Link dongle, on the end of a 50 metre CAT 5 (in a separate building)

All has been working perfectly for a year. All three WiFi devices have
their own SSIDs, and I set the TP-Link dongles to Ch 1 and 13. I can't
remember whether I set the BT HH box to Ch 6, but there's no coverage
overlap anyway.

On Saturday, she phoned me to say there was no internet connection
available from either TP Link devices, but the HH WiFi was still fine.
The TP Links were giving a signal, just an 'empty' one. She tried
several devices, all the same. She'd rebooted everything etc.

I talked her through switching off WiFi on her laptop, and connecting it
via cable LAN to the four port hub. That worked fine, internet
connection available. So that confirmed the powerline chain, and the
little hub were OK. However still no luck with either TP Link device. At
one point attempting to connect via one TP link box, resulted in a BT,
'There seems to be a problem connecting to the internet' web page,
(presumably generated by the HH itself ?).

Yesterday, I set up a spare TP Link dongle I have to duplicate her
arrangement, so I could talk her through the checking DHCP and DNS
settings. She logged on to one of the TP link dongles, and all was in
order, it had been assigned a dynamic IP address by the HH, and it
itself had DHCP server disabled, so the IP address handout is managed by
the HH. It was showing the primary DNS server as the BT HH
(192.168.1.254) (Exactly how I'd configured it a year ago).

Then, we discovered, all was OK, internet connection available on both
devices. Very odd. It certainly wasn't 'finger trouble' on her part,
and the fault was originally detected by her daughter. The whole family
had been trying to make it work, by checking leads, and rebooting all of
Saturday afternoon before bothering me, and it was still the same
yesterday morning, before I rang back.

I can only think there was some sort of DNS problem, with the HH, or
within BT's network ? I don't thing the BT HH allows WAN side access
to remotely examine its parameters ? I might get her a 'proper' ADSL
router, so I can remote access in (she lives 100 miles away) but how
does BT Internet authentication work ?
Is it locked down like Sky's ?



The obvious check in these circumstances is to investigate the LAN
separately from the WAN.

Does the WiFi client get an IP address? (Command line: ipconfig /all)

If so it suggests the LAN is OK - and the DHCP server in the HH is
accessible. You can confirm this by PINGing the router.

It's worth setting the WiFi access points with a static IP address, then
these can be interrogated from the wireless client even if the HH DHCP
service isn't accessible - you would have to configure the client with a
static IP temporarily.

Then connect a PC by wire to the HH and confirm it can be PINGed from
other devices on the LAN - in different locations (by wire and
wireless). You may have to prepare the PC with the necessary firewall
settings.

This should identify any connectivity issues within the LAN.

All the clients however connected should see the same default gateway
and DNS server - the HH itself. Is it possible that some of the
wireless clients are configured with manual DNS settings?

Some HH devices have "Kiddie-proof" settings which do not allow some
clients access to the internet. I've never investigated these; I've
simply disabled it completely, but I've not had to be concerned about
children.

A "proper" router with VPN support is the way to go - you can monitor
all the wireless devices (and other things: printers, NAS disks,
webcams, etc.) that way. There are a few Powerline devices with
IP-addressable management pages but most require a utility running on a
PC - but with a VPN and the help of your user together with VNC or
similar you can have access to the PC to see what is going on. Clearly
this PC should be connected to the router.

Some BT ADSL accounts require a password - if so the documentation with
the service should show it.

I expect the ADSL service has a dynamic IP, if so you will need to
configure the router with a dynamic DNS account; but these are never
entirely reliable. It would be better to get an ADSL service with a
static IP (from Plusnet, Zen, or A&A).

It is possible that the device connected by WiFi directly to the HH had
cached its DNS entries whereas the devices using the other access points
had not; this might explain the difference in ability to connect to the
internet if the HH DNS was not actually working properly. A good test
for this is to ping things on the internet by IP address rather than URL.

I think BT has several DNS servers, some of which are unavailable from
time to time. The router in its default configuration will only learn
the DNS servers at the time it establishes its ADSL connection. I don't
think it is told if the DNS servers become unavailable; but of course
rebooting the router should resolve that.

How certain are you that she actually rebooted the HH ??

If you supply a proper router with VPN capability and change her to a
professional ISP you should be able to monitor the complete system
remotely, including rebooting everything. I support several clients
that way, and it is worthwhile even for apparently quite knowledgeable
and competent clients to make sure that you yourself have tested
everything and seen the actual results.

Good luck.

--
Graham J








  #6  
Old August 4th 14, 12:19 PM posted to uk.telecom.broadband
Roderick Stewart
external usenet poster
 
Posts: 561
Default Strange possible DNS problem with BT Home Hub

On Mon, 04 Aug 2014 11:18:41 +0100, Mark Carver
wrote:

If network access was OK everywhere else before the access points, and
they were producing wireless signals but with no valid network
connection, then that suggests the problem is with the access points,
and I reckon a local IP address conflict would account for it, so it's
something to try.


Yes, that's possible, though the reboots that were attempted *should*
have flushed anything such as that out ?


Well... yes, though that depends on how you define "should". I think
most people would assume it to mean "it would be nice if it did", but
that's not always what happens in real life. I have occasionally seen
some odd effects with networks that don't connect properly unless you
start things in a particular order.

Given that some of your network is going through the mains, there's
always the possibility that a disturbance there could have kicked
something into a non-standard state, or even that your friend could
have unplugged one of the powerline adaptors to use the Hoover without
thinking about it, or even remembering it.

Some supposedly "automatic" things work better than others, so my
inclination is generally only to use automatics where they give a
genuine advantage. I don't think there's a particular advantage in
automatic addressing in the fixed parts of a network that you have to
make the effort to set up anyway, so you might as well set up the
addresses too. Good luck with it anyway.

Rod.
  #7  
Old August 4th 14, 01:33 PM posted to uk.telecom.broadband
Mark Carver
external usenet poster
 
Posts: 458
Default Strange possible DNS problem with BT Home Hub

On 04/08/2014 11:30, Graham J wrote:


If you supply a proper router with VPN capability and change her to a
professional ISP you should be able to monitor the complete system
remotely, including rebooting everything. I support several clients
that way, and it is worthwhile even for apparently quite knowledgeable
and competent clients to make sure that you yourself have tested
everything and seen the actual results.

Good luck.


Thank you, and thank you for your thoughts !!

All points noted. I'm fairly certain the HH was rebooted, but of course
I can't be 100% sure. To be honest, I'm surprised this has been the only
problem in a year, over the winter she was suffering no end of power
cuts, and brown outs, and I was amazed this chain of devices managed
to sort themselves out, and power back up all working every time.

Most of the devices in use are mobile phones, and tablets. The nearest
thing to a PC in the house is a single lap top.

I'd already been talking to her, about upgrading to proper ISP, I was
slightly dismayed a couple of years ago to discover she'd gone for BT,
but previously it was TalkTalk !!

Connection does indeed have a dynamic IP address. I do use DynDNS
on Mother-in-Law's and my parent's router (come on Plusnet, supply a
static option on your 'starter' account please ?) and it does the job,
just can take a few mins to refresh fully after reboots etc, which is a
pain

--
Mark
Please replace invalid and invalid with gmx and net to reply.
  #8  
Old August 4th 14, 11:53 PM posted to uk.telecom.broadband
Brian Gregory
external usenet poster
 
Posts: 123
Default Strange possible DNS problem with BT Home Hub

On 04/08/2014 11:18, Mark Carver wrote:
On 04/08/2014 11:06, Roderick Stewart wrote:


Is it possible to set static IP addresses for the access points
(dongles) themselves, while keeping DHCP for devices fed through them?


Yes, it is. In fact I've done that on another 'remote' install of mine.

If network access was OK everywhere else before the access points, and
they were producing wireless signals but with no valid network
connection, then that suggests the problem is with the access points,
and I reckon a local IP address conflict would account for it, so it's
something to try.


Yes, that's possible, though the reboots that were attempted *should*
have flushed anything such as that out ?


Sometimes the order things are rebooted matters.
Also EVERYTHING must be rebooted (powered off and on again) including,
for example, network switches and homeplugs.



Who knows how it happened (if that is what happened) but just to avoid
this possibility, I use static IP addresses on all my network devices
that are in fixed locations, and only use DHCP for portable devices
such as laptops and phones. Many routers are configured by default
with DHCP starting at a high number such as 64 or 100, so you can use
anything below that for fixed addressing, so you may not even need to
reconfigure the Home Hub.


Indeed, well worth a punt I think. I'm visiting in a couple of months,
so I'll do it then. If it fails again before then, I'll talk my friend
through the process remotely (she's getting very good at logging onto
http set up menus now !)





--

Brian Gregory (in the UK).
To email me please remove all the letter vee from my email address.
  #9  
Old August 5th 14, 08:30 AM posted to uk.telecom.broadband
Graham J[_2_]
external usenet poster
 
Posts: 723
Default Strange possible DNS problem with BT Home Hub

Brian Gregory wrote:
On 04/08/2014 11:18, Mark Carver wrote:
On 04/08/2014 11:06, Roderick Stewart wrote:


Is it possible to set static IP addresses for the access points
(dongles) themselves, while keeping DHCP for devices fed through them?


Yes, it is. In fact I've done that on another 'remote' install of mine.

If network access was OK everywhere else before the access points, and
they were producing wireless signals but with no valid network
connection, then that suggests the problem is with the access points,
and I reckon a local IP address conflict would account for it, so it's
something to try.


Yes, that's possible, though the reboots that were attempted *should*
have flushed anything such as that out ?


Sometimes the order things are rebooted matters.
Also EVERYTHING must be rebooted (powered off and on again) including,
for example, network switches and homeplugs.

[snip]

The power-on order should be router first, then powerline devices, then
APs and other things with IP addresses.

My recommendation for the things which need static IP addresses is to
configure the router to bind to the MAC address, and choose IP addresses
outside the DHCP scope of the router. On some routers this might not be
possible, they can only bind addresses within the DHCP scope. And on
other routers (HH and the like) you may have no control over the IP
address but the router may remember it so it becomes consistent. If the
router has no binding mechanism then manually configure the device,
again using an address outside the DHCP scope.

Then, manually configure all the devices to have the IP address, default
gateway, and DNS settings that have been assigned by the DHCP server.

That way the devices are guaranteed to have your chosen IP paramaters,
even if the router is not working.

I have found a case where this fails. The TP-LINK TL-wpa281 (which came
in a kit with the TL-PA211 powerline adapter) claims an IP address for
itself, but it does not use DHCP - because the router does not show it
in the list of IP addresses it has issued. So the router has no control
over the address, it can't bind it to the MAC address. My guess is that
the TL-wpa281 finds out the IP address of the DHCP server, then
arbitrarily chooses its own IP address within that subnet. It isn't
consistent across power off/on. It may check whether its choice is
currently unused, but this does not prevent it from choosing an address
which is manually configured in another device as yet not switched on.

No doubt I could investigate further with Wireshark or the like ...

--
Graham J

  #10  
Old August 5th 14, 12:17 PM posted to uk.telecom.broadband
Roderick Stewart
external usenet poster
 
Posts: 561
Default Strange possible DNS problem with BT Home Hub

On Tue, 05 Aug 2014 08:30:54 +0100, Graham J
wrote:

My recommendation for the things which need static IP addresses is to
configure the router to bind to the MAC address, and choose IP addresses
outside the DHCP scope of the router.


You can get yourself into terrible knots trying to set up MAC
filtering unless you know exactly what you're doing and take great
care not to make mistakes. Get one digit wrong in the MAC address of
the computer you're using to set it up, and as soon as you click the
button to switch the filtering on, you'll be completely disconnected.
The only way out then is to perform a hardware reset of the router,
restoring everything, including wireless settings, to factory
defaults, so you'll have to start all over again, which is tedious.

I'll leave you to guess how I know this.

The procedure of least effort is to note the IP addresses the router
hands out automatically, and if they seem to start from a particular
value - 64 and 100 are common choices - just set static addresses that
are below that value on all your fixed computers and other devices.
Make sure they're all different of course. For gateway and DNS
settings, put the address of your router. It'll be the same as the
others but probably ending in 1 or 254. I've always found this to be
enough to make things work.

Rod.
 




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