Ah, another unhappy coms customer. My connection has been better of late - still slower than pre-cutover, but my current session is now almost 9 days so there is hope! I am using public dns though instead of coms.
Anyway, I'm sure more knowledgeable people than me will be along soon with more ideas - but it might be worth trying a tracert to www.bbc.co.uk
and posting the results back here. Also, info from your router - model, sync speeds, snr, current session length, etc.
Are there any errors reported in the router logs? Does it show disconnects & reconnects?