Looking for some additional help I spoke to my ISP who ran a line test and lo and behold, there's an earth fault. BT was out a couple of weeks earlier to sort out a bad connection - at that time it was traced to water ingress into one of their cabinets. This time it was traced to a connector outside the front door that the damp had got to. All working OK now; down speed is indicated at 7200000 and SNR margin is 8-9 dB so fingers crossed it stays that way.

I too have this problem - suddenly the CRC errs increase dramatically and the download speed drops to virtually unusable speeds. I then have to reboot.

This is a 2820vn running firmware ADSL Firmware Version: 3.3.7.1_232201 (Annex A)

Has anyone solved this?