jmn wrote: have a look at http://www.rmnjmn.demon.co.uk/DrayTek/Data_10Jul12.JMN

Your not on Demon's C&W LLU by any chance are you ?

babis3g: Thanks for comment. DrayTek suggested trying, in this order:
Vigor2820_V3.3.7.2_A__STD.zip (which is 211011)
Vigor2820_V3.3.7.2_A_2471201.zip (which is Annex M)
Vigor2820_V3.3.7.2_A_211801.zip (which I have already tried without improvement)

I have not had time at the moment to experiment with the first two but will do so when I can. In the early days of ADSL2+ I did compare G.DMT with G.992.5 but this may be worth repeating now that the line as changed.

rothers: yes, I am on C&W LLU. I need to check my records when this was done and compare stability in the weeks before and the weeks after the changeover to C&W. This comparison might be illuminating...

John

I had dreadful problems with a 2820 on Demon's C&W LLU. SNR would start off fine but then reduce to a ludicrously low 3dB at which point bandwidth ground to a halt with no attempt to resysnc. A manual reboot sorted everything for a few days. Also had problems with ADSL line dropping on incoming BT phone Calls.

Have since migrated to AAISP on BT and everything is fine. Never have to touch the 2820 now, it maintains a healthy SNR of 9dB with higher sync speeds than I was getting with Demon over the same line.

rothers: Interesting that you also have problems with ADSL line dropping on incoming BT phone calls. I also picked this up from others via a Google search. I use dynamic monitoring of my line - when CRC count reaches around 20,000 or more, experience shows that data throughput can drop to less than 100 kBps. My monitor software will then reboot (telnet: adsl reboot) the router and report in a log that it has done so. If I were to wait for an external line resync, the system would become unusable. My scheme, at least, maintains a reasonable data rate at all times, albeit with the penalty of several reboots a day. My plots are automatically uploaded every hour and change once every 7 days.

Thanks for your comment from someone also on C&W LLU. Very helpful.

Perhaps it is time to follow this up with Demon rather than Draytek.

John