Something wrong with Plus Net DNS servers or not compatible with VPN?

[#1]

I have been experiencing VPN connections being dropped and also Microsoft teams calls failing (via VPN or not) with me being disconnected which given I work at home is an issue.  It’s got steadily worse over recent weeks and today got so bad I couldn’t do anything of use this morning.

I can use different VPN clients and different access points into the company network and it’s the same regardless. 

It’s been particularly frustrating as I work in software development and when debugging multiple processes if the VPN kicks me off recovering that and setting up the environment is very time consuming. That happened several times yesterday so when today’s problems occurred and work ground to a halt I managed to locate the event log for the VPN and it was full of DNS Client Events. Specifically:

Event ID:      8015

The reason the system could not register these RRs was because the update request it sent to the DNS server timed out. The most likely cause of this is that the DNS server authoritative for the name it was attempting to register or update is not running at this time.

So I changed the DNS servers in my router (TP Link Archer 2800) to the Open DNS servers and the problems went away.  No VPN connection drops and much faster response times all afternoon and no more 8015 events after changing the DNS server configuration.

Doing a bit of digging I found that the default configuration in Windows 10 for the DNS under “Advanced TCP/IP settings” for the computers network adapter is “Register this connection’s addresses in the DNS” and so it appears attempts to do that are failing.

I can connect to Teams without establishing a VPN connection and I have been kicked off there so I am not convinced it is an issue specific to the VPN connection.

So is this failure to register a Plus Net DNS issue?

I will monitor the VPN event log tomorrow to confirm those errors have indeed vanished since changing DNS servers but am I correct to assume the correct Plus Net DNS servers to use are 212.159.6.9 & 212.159.6.10  (that was my configuration before changing to Open DNS)?

[#2]

Hi there,

I'm really sorry to see you're having connection issues while trying to work from home. 

The DNS servers you've used are definitely correct, you can also use 212.159.13.49 and 212.159.13.50

I've checked things our side and I can't see any problems. Do you still have our router you could try? 

Also, if you change the DNS servers back to ours in your router, try running a traceroute to the VPN endpoint IP. 

This may shed some light on the issue. Let me know how it goes. 

[#3]

I probably do have the old plus net router but its a pretty ancient one since I have been a customer a long time and it was swapped out to give better wi-fi so I am not keen on reinserting it into the system when other than my VPN issue everything else seems to work.  In any case I think the tracert's below show it isn't a router issue.

I did the tracert and this is what I found:

Tracing route to cdns01.plus.net [212.159.6.9]
over a maximum of 30 hops:

1 <1 ms <1 ms <1 ms ARCHER_VR2800 [192.168.1.1]
2 4 ms 3 ms 4 ms 172.16.17.152
3 * * * Request timed out.
4 13 ms 13 ms 12 ms 140.hiper04.sheff.dial.plus.net.uk [195.166.143.140]
5 * * * Request timed out.
6 12 ms 12 ms 12 ms cdns01.plus.net [212.159.6.9]

Trace complete.

So two timeout's at steps 3 & 5

I also traced the Open DNS server: 

tracert 208.67.222.222

Tracing route to dns.opendns.com [208.67.222.222]
over a maximum of 30 hops:

1 <1 ms <1 ms <1 ms ARCHER_VR2800 [192.168.1.1]
2 4 ms 3 ms 4 ms 172.16.17.152
3 * * * Request timed out.
4 11 ms 11 ms 11 ms 140.hiper04.sheff.dial.plus.net.uk [195.166.143.140]
5 10 ms 9 ms 9 ms peer7-et-3-0-5.telehouse.ukcore.bt.net [109.159.252.188]
6 10 ms 9 ms 9 ms 166-49-214-194.gia.bt.net [166.49.214.194]
7 12 ms 10 ms 10 ms gi0-0p226.rtr1.lon.opendns.com [195.66.237.70]
8 11 ms 11 ms 11 ms dns.opendns.com [208.67.222.222]

Same timeout at step 3 but only the one.

I tried the Goggle DNS servers and this is the only one that gave no timeouts:

C:\Users\e1012917>tracert 8.8.8.8

Tracing route to dns.google [8.8.8.8]
over a maximum of 30 hops:

1 <1 ms <1 ms <1 ms ARCHER_VR2800 [192.168.1.1]
2 4 ms 3 ms 3 ms 172.16.17.152
3 * 11 ms 11 ms 141.hiper04.sheff.dial.plus.net.uk [195.166.143.141]
4 13 ms 13 ms 13 ms 140.hiper04.sheff.dial.plus.net.uk [195.166.143.140]
5 13 ms 13 ms 13 ms peer3-et0-0-5.slough.ukcore.bt.net [194.72.16.66]
6 14 ms 13 ms 13 ms 195.99.126.137
7 16 ms 16 ms 16 ms 216.239.62.75
8 13 ms 13 ms 13 ms 172.253.66.101
9 14 ms 14 ms 13 ms dns.google [8.8.8.8]

Trace complete.

No timeout's at all for google but more hops.

Tried the alternative Plus Net DNS server:

tracert 212.159.13.49

Tracing route to cdns01.plus.net [212.159.13.49]
over a maximum of 30 hops:

1 <1 ms <1 ms <1 ms ARCHER_VR2800 [192.168.1.1]
2 4 ms 3 ms 3 ms 172.16.17.152
3 * * * Request timed out.
4 12 ms 12 ms 12 ms 136.hiper04.sheff.dial.plus.net.uk [195.166.143.136]
5 11 ms 11 ms 11 ms 195.99.125.139
6 11 ms 11 ms 10 ms cdns01.plus.net [212.159.13.49]

Seems better than the original 212.159.6.9 and similar to Open DNS.

All the above results are repeatable i.e. happen every time I do the tracert for those IP's.

So for both Plus Net servers and OPen DNS the timeout at hop 3 is normal I think (and it's odd this doesn't occur using Google so must be going to something that does respond to tracert) so the issue seems to be the hop at step 5 when using 212.159.6.9.

[#4]

Those traceroutes all look fine to my eye and don't show any issues.

Some hops will time out but it's likely that the routers at that end are "rate limiting ICMP" which means they're prioritising the routing of traffic rather than responding back to you. The main thing is that the traces are completing.

Appreciate the reluctance to try a different router, but I think it's the next logical step to try to get to the bottom of the issue.

As you've worked around the issue by using other DNS servers, it may be worth leaving things as they are though.

[#5]

I am going to try the alternate servers tomorrow and see if the VPN issue comes back.   If it does I may just change Windows 10 config on my work laptop to use the Open DNS servers rather than use the automatic option which is to use those offered up by the router , leaving the router on plus net because outside of the VPN issue things are fine.

That said we do experience the odd slow down streaming 4K TV on Netflix which given the speed tests I have done are always fine is a bit strange so makes ne suspicious if that is due to a similar.