I've been running a 2762 on my BT infinity line for several months now replacing a HH5B as I wanted control of DNS, VLAN etc.

3 weeks ago I updated my 2762 to 3.9.1_BT and not long after this at around 3-3.30pm every day the connection goes from 70/20 down to 20/20 (and is all over the place) and can only be fixed by a reboot of the router. I have checked this speed via a wired windows client but my wireless and wired IPTV clients also suffer (IPTV goes down completely).

I tried to go back to the previous firmware but this didn't help.

If I put my HH5B back in place then I don't notice the same problems so I suspect it's something to do with my 2762 and that the firmware upgrade either triggered it or there was a change at the cabinet/exchange at the same time. I notice on BT's service status page that there are lots of broadband problems at the moment, but not specifically in my area (0161).

At the weekend I left all my kit off for 2 hours to try and reset the line but that didn't help.

Any ideas how I should diagnose this please?

I was about to pull the trigger on a 2862 off ebay last night in case it's my 2762 for some reason but no reason to spend £140 if it's my line..