yes I do.

I’ve run out of configuration suggestions and it seems to be that the link between the Openreach ONT and the Draytek fails for unknown reasons.

I wish I was convinced that replacing the Draytek would fix this but I’m not.

Putting Plusnet’s Hub 2 in the chain (as previously suggested) in bridge mode is an obvious next step.

It could easily be the ONT.

Yes I am of a similar mind. I did wonder about the ONT, I seem to be able to twist it on the wall as if it isn't screwed down tight, but that may be normal. I will try the Hub2 bridged when I am able to spend some time there (its a simple job but I know it will take upwards of an hour as simple jobs do) and I am also thinking the same as you about replacing the Draytek - especially with another Draytek. It's currently down, has been for over 24hrs now, but one last thing I might try is switching back to full hardware acceleration without the LAN traffic graph once I regain connection. It did stay up for 10 days before I turned on traffic graph to see what LAN things were connected (albeit with a few short lived drops). If that works, I would put it down to lack of processing speed. If the Hub2-bridge works then its looking more like a new router.