ADSL Max Premium upload question

My ADSL Max Premium connection is usually very stable (weeks between drops), and I usually sync at 8128Kbps down and 832Kbps up, with a profile of 7.15Mbps (as would be expected).

The router gives an "attainable" upload rate of 1.2Mbps which would be the case for ADSL2+, but obviously not for ADSL Max Premium.

This morning the router reconnected and the upload sync is now only 640Kbps, with an "attainable" rate of 752Kbps. The profile is still 7.15Mbps.

The SNR for the upload has dropped to 6dB (usually 9dB at 832Kbps), while the download is still at 11dB.
There's no obvious difference in the tones. and there has been 1 upload FEC error in the past couple of hours (that is unusually high for my line, but is still only 1!).

I'm aware that the profile is adaptive, but it hasn't changed - and does it affect uploads anyway?

Any suggestions on how to recover the upload speed (resyncing hasn't helped)?

Turn off the new noise source!

If the SNR has dropped from 9dB which indicated there is headroom above the max 832kbps to 6dB where there is no headroom, then there has almost certainly been a change in the noise levels. Have you or your neighbours added any new electrical or electronic items? Have you moved the modem or put a TV next to it?

Do not keep trying resyncs though - that can make it worse.

Your 7.15 IP Profile is for downstream. If you are getting it from the Further Diagnostics of the BT Wholesale Performance tester there may or may not be a figure for IP Profile in the upstream box. I can't remember for ADSLx. It is there for FTTC but is always showing the maximum for the product, not based on actual connection speed.

Turn off the new noise source!

I'm not sure what/where any new noise source could be. Nothing has changed at my end - I'm using a Vigor 2860n+ router with recent firmware, in the master socket with an ADSLNation faceplate, and no extension wiring attached. That is on a UPS (we get occasional power cuts/brownouts), so is well filtered from any mains noise.

No new electrical/electronic equipment, and the nearest neighbour is >200metres away. The phone wire runs underground in a straight line to the exchange and probably doesn't pass within 30 metres of any property along the way (and there aren't many of those).

There is no audible noise on the line, and no new notches in the tone graphs.

There is the one (1) upload FEC error today, but no other indication of any interference/noise apart from the drop in SNR.

Since the profile is at the maximum, and there doesn't appear to be a separate upload profile, is the upload likely to reset at some point?

DSL will not force a resync to increase speeds, that needs your intervention, so once you appear to have spare noise margin on the upstream its worth a resync