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TPlink WPA4420 powerline adaptor sometimes becomes my PC's DNS server!



 
 
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  #1  
Old May 18th 19, 03:33 PM posted to uk.telecom.broadband
NY
external usenet poster
 
Posts: 492
Default TPlink WPA4420 powerline adaptor sometimes becomes my PC's DNS server!

I've got a Plusnet Hub One router and all the PCs on my network are set to
use normal DHCP to get their IP and DNS server.

One PC, Windows 7 Home Premium, is connected to the router by a pair of
Powerline devices (one in the router, one that the PC is plugged into)
because the wifi signal is a bit weak and it's not practical to run an
Ethernet cable. Everything has worked fine.

I've bought a TPlink WPA4420 powerline adaptor which has both Ethernet ports
and a wifi access point, which we'll use at our new house; I'm trying it out
in the present house.

And when it's plugged in to the mains, my Win 7 PC occasionally gets into a
strange state: it cannot resolve web or mail server addresses.

On closer inspection, using "ipconfig /all" I can see that the DNS server is
set to the IP address of the TPlink device, instead of being set to the
router's IP address:

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . : lan
Description . . . . . . . . . . . : Broadcom NetLink (TM) Gigabit
Ethernet
Physical Address. . . . . . . . . : [a valid MAC address]
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : [a sensible-looking IPv6
address](Preferred)
IPv4 Address. . . . . . . . . . . : 192.168.1.70(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Lease Obtained. . . . . . . . . . : 13 May 2019 23:35:03
Lease Expires . . . . . . . . . . : 19 May 2019 14:36:15
Default Gateway . . . . . . . . . : 192.168.1.254
DHCP Server . . . . . . . . . . . : 192.168.1.254
DHCPv6 IAID . . . . . . . . . . . : [censored - just in case]
DHCPv6 Client DUID. . . . . . . . : [censored - just in case]
DNS Servers . . . . . . . . . . . : 192.168.1.83
NetBIOS over Tcpip. . . . . . . . : Enabled


192.168.1.83 on the penultimate line is the address of the TPlink. Normally,
DHCP sets the DNS Servers address to 192.168.1.254, the router's address.


I've got round it by configuring a static DNS address of 192.168.1.254, but
that's a bit of a cop-out.


Has anyone ever seen this: where a router's DHCP server hands out the IP
address of a device on the LAN, in the DHCP scope? Is it a weird interaction
between the router's DHCP server and the TPlink powerlink adaptor.

  #2  
Old May 18th 19, 03:36 PM posted to uk.telecom.broadband
Andy Burns[_5_]
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Posts: 390
Default TPlink WPA4420 powerline adaptor sometimes becomes my PC's DNSserver!

NY wrote:

Is it a weird interaction between the router's DHCP server and the
TPlink powerlink adaptor.


Having two DHCP servers on the same subnet is almost always a mistake on
a home network, disable DHCP on the TPLink.
  #3  
Old May 18th 19, 03:57 PM posted to uk.telecom.broadband
NY
external usenet poster
 
Posts: 492
Default TPlink WPA4420 powerline adaptor sometimes becomes my PC's DNS server!

"Andy Burns" wrote in message
...
NY wrote:

Is it a weird interaction between the router's DHCP server and the TPlink
powerlink adaptor.


Having two DHCP servers on the same subnet is almost always a mistake on a
home network, disable DHCP on the TPLink.


Ah, do you think the powerline adaptor has a DHCP server built into it? I
didn't think of that. Two DHCP servers (especially with overlapping scopes)
would be a disaster.

I can't see anything in its config pages that talks about DHCP server.

  #4  
Old May 18th 19, 04:15 PM posted to uk.telecom.broadband
Graham J[_3_]
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Posts: 58
Default TPlink WPA4420 powerline adaptor sometimes becomes my PC's DNSserver!

Andy Burns wrote:
NY wrote:

Is it a weird interaction between the router's DHCP server and the
TPlink powerlink adaptor.


Having two DHCP servers on the same subnet is almost always a mistake on
a home network, disable DHCP on the TPLink.


Did you configure the TPlink WPA4420 yourself in any way?

It's likely that the factory configuration is as a stand-alone wireless
access point, so it broadcasts its SSID and WiFi devices will be able to
connect using the security key printed on the TPlink WPA4420; and
importantly it might run its own DHCP server as implied by Andy Burns.

It follows that any device that connects to it will receive IP
parameters supplied by the TPlink WPA4420. Why the client receives
values that are a mix of the TPlink WPA4420 and the Plusnet Hub One
router is anybody's guess.

So, power of all PCs, laptops, WiFi devices, etc., bar one (this should
avoid confusion).

Connect a PC to your router by Ethernet cable. Check it can see the
router etc.

Plug the two TPlink devices into the mains. Connect the PA4010 adapter
by Ethernet cable to the router. Follow the manual to pair the WPA4420
with the PA4010. At this stage your PC should be able to see the TPlink
WPA4420 by IP address, but you may need to install a utility from TPLink
to achieve this.

Configure the TPlink WPA4420 with a suitable IP address, and make a note
of it. Ensure that its DHCP server is disabled. It may be necessary to
specify that its WiFi clients are allowed to broadcast on the LAN so as
to find the Plusnet Hub One. Set up the WiFi details. If you want your
wireless clients to roam between the Plusnet Hub One and the TPlink
WPA4420 normally you should use the same SSID and security key, but a
different non-overlapping channel. Having said that, roaming sometimes
depends on the capabilities of the client device so you may not be able
to get this to work.

Now power up another PC. Connect it to the TPlink WPA4420 by Ethernet
cable and verify that it gets the correct IP parameters. Confirm it
sees the internet OK. If you have file sharing configured between the
two PCs check that this works, and files are copied from one PC to the
other at reasonable speeds.

Repeat the test with your second PC connecting to the TPlink WPA4420 by
WiFi.





--
Graham J
  #5  
Old May 18th 19, 04:25 PM posted to uk.telecom.broadband
Andy Burns[_5_]
external usenet poster
 
Posts: 390
Default TPlink WPA4420 powerline adaptor sometimes becomes my PC's DNSserver!

NY wrote:

Ah, do you think the powerline adaptor has a DHCP server built into it?


Actually your ipconfig/all shows that the PC got its IP addr by DHCP
from the router, sure it hasn't got manually set DNS, rather than auto?

Maybe the TPlink is acting as a DHCP relay between the wifi side and the
power-over-mains side and somehow overwriting its own IP addr into the
DNS settings? Does the TPlink have the router as its DNS server?

  #6  
Old May 22nd 19, 03:59 PM posted to uk.telecom.broadband
Woody
external usenet poster
 
Posts: 737
Default TPlink WPA4420 powerline adaptor sometimes becomes my PC's DNSserver!

I had the same issue using a TP-Link access point which is multi function.

There is a simple solution: give the TP-L unit a fixed IP address
outside the master router DHCP range and turn the TP-L DHCP off. Then it
will never seek an address as it already knows what to use, and as DHCP
is off the only place a DHCP address can then come from is the main router.

Personally I have fixed all my internal IP addresses using the router
address reservation facility and I never have any problems.


--
Woody

harrogate three at ntlworld dot com
  #7  
Old May 22nd 19, 04:27 PM posted to uk.telecom.broadband
NY
external usenet poster
 
Posts: 492
Default TPlink WPA4420 powerline adaptor sometimes becomes my PC's DNS server!

"Woody" wrote in message
...
I had the same issue using a TP-Link access point which is multi function.

There is a simple solution: give the TP-L unit a fixed IP address outside
the master router DHCP range and turn the TP-L DHCP off. Then it will
never seek an address as it already knows what to use, and as DHCP is off
the only place a DHCP address can then come from is the main router.

Personally I have fixed all my internal IP addresses using the router
address reservation facility and I never have any problems.


Unless I'm missing something, there doesn't seem to be a DHCP server in the
TPlink WPA442 powerline access point. I've just packed up the device in
readiness for moving house tomorrow (about time too!) so I can't test it
until tomorrow - or whenever I get some spare time when I'm not unpacking.
As a short-term workaround when the device is plugged in, I've set a static
DNS address on the PC that is affected but still get IP/subnet/gateway from
DHCP.

I'll give the device a fixed IP address, either as a static one configured
at the device or else (preferably) as a reserved IP via DHCP on the router.

I tend to give commonly-user "server" devices reserved IP addresses in case
I need to access them by IP because the name service (NetBIOS, probably)
doesn't always work for web addresses. My Raspberry Pi runs a PVR program
that has a web interface on one port and runs weather station data-logging
software that has a web interface on another port, so to access them from
other computers/phones on my LAN I have a URL of http://192.168.1.72:9981 or
8998 in the bookmarks.

 




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