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DNS problems on my router

chris1610
Grafter
Posts: 30
Registered: 31-03-2017

DNS problems on my router

I've just had a extended period of DNS not working on several devices. Only my main Windows 10 PC which uses Google DNS servers was functioning.   

 

Rebooting hub one router resolved it. So I assume problem was at router level rather than Plusnet DNS servers. (Router is using 212.159.6.10 and 212.159.6.9 .)

 

Is there anything I can do to prevent this happening again? 

8 REPLIES
chris1610
Grafter
Posts: 30
Registered: 31-03-2017

Re: DNS problems on my router

By "extended period" I mean of the order of half-an-hour or so. Before I moved from ADSL to fttp I used to occasionally lose DNS for a few minutes on my PC, which is why I changed to using Google DNS servers.

bill888
Seasoned Pro
Posts: 801
Thanks: 103
Fixes: 20
Registered: 18-10-2008

Re: DNS problems on my router

Sounds like the DNS server on the Hub One may be stopped working which is unusual, or perhaps the hub's internal DNS server couldn't communicate with Plusnet's DNS servers.

 

Unfortunately, the Hub One doesn't permit DNS settings to be modified, and it also doesn't offer 'advanced' DHCP settings.

 

I've had issues in the distant past where the DNS server on a router seems to just fail.  To improve reliability, I use routers which offers support for DHCP Option '6' where I can specify primary and secondary DNS servers.  

The DHCP server, sends these two DNS server addresses to connected clients.  The clients go direct to the specified DNS servers to resolve any DNS names.  ie. they do not use the router's DNS server.

dhcpOption6.jpg

Gel
Pro
Posts: 1,386
Thanks: 133
Fixes: 10
Registered: 02-08-2007

Re: DNS problems on my router

You don't clarify what router; unless it's a PN Hub One type you can change the Router's DNS choice

to Google.

Community Gaffer
Community Gaffer
Posts: 12,852
Thanks: 672
Fixes: 65
Registered: 04-04-2007

Re: DNS problems on my router

Hard to pass comment on this without further detail i.e:

  • are problematic devices connected wirelessly or wired (or both)?
  • If wireless, does the problem persist if you separate the 2.4GHz and 5Ghz wireless channels?
  • If you log into the router interface, and browse to Advanced > Home Network > DHCP Table, can you still see the DHCP leases assigned to each client?
  • Shortly after the problem occurs, is there anything odd in the logs if you browse to Troubleshooting > Event log in the router interface?
  • If you experience the problem from a Windows or Unix device (or Macbook/iMac), then what does an ipconfig or ifconfig show whilst the problem is evident? (happy to elaborate on this one, if specific instructions are required).
  • Can you browse to a site using it's IP address when the 'DNS failures' are occurring? e.g. http://216.58.206.99

No doubt more stuff to consider, but that's a good starter for ten.

Bob Pullen
Plusnet Products Team
If I've been helpful then please give thanks ⤵

chris1610
Grafter
Posts: 30
Registered: 31-03-2017

Re: DNS problems on my router

The devices I tested were android phone and tablet connected wirelessly, plus a windows 10 computer connected via powerline.

The wireless devices were using separated 5G channel.

 

Didn't see anything in the router log when I looked.

For other questions, think I will have to wait for it to happen again. (Though I think the fact that a Windows 10 computer hard-coded to use Google DNS was working surely rules out most other issues?)

 

 

chris1610
Grafter
Posts: 30
Registered: 31-03-2017

Re: DNS problems on my router

I should add that a work laptop running windows 7 was also working, but presumably it was using work DNS via VPN.

chris1610
Grafter
Posts: 30
Registered: 31-03-2017

Re: DNS problems on my router

Just to clarify, there were two windows 10 computers, one without customised DNS got DNS failure, one with Google DNS didn't.

 

The DNS failures were on multiple sites. (At least four tested on Android phone.)

chris1610
Grafter
Posts: 30
Registered: 31-03-2017

Re: DNS problems on my router

I think this happened again today, though didn't investigate it as thoroughly as last time. A router reboot fixed it. Router had been up 25 days since previous reboot, which was an automatic one for a firmware upgrade. (The first time it happened, router had been up for 20 days.)