Well, I'll throw a curveball here and state that I was experiencing the same high latency.. even with a laptop plugged into my router... It makes no sense.
I used Teamspeak, a VoIP program which has a really good connection quality monitor built in. I also ran several speed tests through wired and wireless. When I first plugged it in wired on teamspeak, I was getting 20ms ping and it was perfect, after 5 minutes.. it went up to 200-400ms and to its usual laggy self again. I tried again on wireless and it was a very similar result - all I had to do was run a speed test and the latency stayed out the roof even after the test was complete. It's like any 'hard work' it has to do knocks it into high latency mode and it rarely recovers, lol.
Tried resetting the router again and even unplugged everything - it did go back to 20ms briefly before rocketing up to 200ms+.
I turned off the coordless phone nearby and there's no difference. I can't think of any other appliances in the house that could be interfering so badly.
Wifi channels in the area;
http://i.imgur.com/QGyM0t0.png
As for my thinkbroadband chart.. it reports everything like its all normal. There are 3 red spikes this evening, but that was when I unplugged the router etc. I tried changing DNS servers today as well just to see if it made any difference but it didn't.
as an FYI, my PC network adapter doesn't pick up the 5GHz band... although the family is on iphones/ipads which use it and they report that pages load slow as if something is hogging bandwidth/bad signal.
But again, let me reiterate the fact sort of problem happens every few months.. so -normally-, the load times are fine and everything is flawless, no latency issues, no nothing.
I'll see what its like tomorrow and if it plummets back into latency issues at 5pm i'll post my findings on the talktalk community forum and try to get some official support on this as well. Thanks for all your guys' help so far. I'd still appreciate any suggestions.
current stats;
http://i.imgur.com/fnbMyDm.png (although i did reset router a few hours ago so these show less errors than in earlier posts)
Upstream noise safety coefficient (dB):
7.3
Downstream noise safety coefficient (dB):
6.3
Upstream interleave depth:
0
Downstream interleave depth:
0
Line standard:
VDSL
Upstream line attenuation (dB):
12.5
Downstream line attenuation (dB):
6.3
Upstream output power (dBm):
-1.7
Downstream output power (dBm):
Edited by deleted (Wed 10-Jun-15 22:43:18)