Yes, it could be DLM. DLM usually happens first 10 days after switching. Now some people report that they don't experience this when switching FTTC providers.

I however, have experienced it on 3 occasions thus far. When I was with Plusnet ADSL and then when I switched to TalkTalk FTTC in February 2020 for 10 days it occurred before it stabilized.

Then I switched to BT FTTC just over a year ago and the same experience occurred for me again.

10 days hasn't yet passed for you to test. But the fact that this is happening at night time is a typical indicator that it is DLM. Because my experience was exactly like yours between 1 to 1:30am.

Your SNR is very good. If you're getting 10-13dB I'd believe there's little line interference. But of-course DLM can also increase the SNR if it detects that your sync is not being maintained at lower dB.

I sync at 3dB but I'm on 80/20. It is possible that if I downgraded to 40/10 then I'll sync at higher than 3dB because lower speeds usually produces higher SNR and higher speeds reduces SNR.

Also keep an eye on router firmware update. In your router stats it should show the date for the last firmware update. During this time at night router firmware updates can also occur.

4 days ago my BT Smarthub 2 restarted and I checked the Firmware updated:Fri Sep 1 01:03:13 2023. I knew this was router firmware upgrade.

When you switch to a new ISP your router may be upgraded multiple times for the latest router firmware since your stock router that is shipped is outdated. You can't disable ISP router from updating firmware automatically. The only way is to have your own third party router.

Also during the first 10 days when switching you must not turn your router off. I know some people do that and that can mess up with DLM finding a stable line in which, DLM will continue past 10 days until it finds a comfortable spot where it no longer resyncs. Power outages can also trigger DLM as DLM interprets this as a line fault, it can't distinguish between a connection loss due to power cut or due to line noise interference.

Thank you. Yea this is a 3rd part router and firmware up to date so nothing going on there.

If its DLM im not sure what its actually doing. The 1st resync lowered by pings by half (16 to 6ms i believe) so maybe it turned interleaving or some error detection off i dont know.

But considering all resync events have meant i have resynced at full 40/10 then its not banded me or anything on a lower profile. If anything its the opposite as SNR is getting better while maintaining the same sync speed.

Interestingly Talk Talk (who Pulse8 use) downdetector did register a mini spike of people report issues around the same time mine went down last night, so maybe it was something else that triggered it