Testing via hardwire through superhub2 router via PC.
Last night instead of simply turning the router on and off which I have tried in the past but with no success, I left it off all night in the hope that when it was turned on again the connection would be "renegotiated", this seems to have done the trick as speeds are now back to normal and no downstream Post RS Errors, however already have >100k Pre RS errors on one channel with the lowest Power Level of 37.36dB. Also the uplink has no T3 timeouts when there were >10k previously.
Anyhow it seems the turn off for a long period did the trick, thanks for getting back to me so quick, lets hope this problem does not come back.
Downstream power levels are bordering on the low side, though still within tolerance and worth keeping an eye on.
Checking the historic data from around 24-28/12 I can see that there was an an issue with low SNR and FEC on your cable upstream, which may have been the issue here, this has since recovered and looking much healthier.
How are the speeds now, drop us a quick update when you have a moment and we'll gladly investigate further if problems are still evident.