Along with many other people, I have suffered frequent re-boots, especially since the Oreo8 update. I tried all sorts of the tweaks suggested in this forum until I accidentally stumbled on the problem.

The culprit in my case is a Panasonic PVR connected to the TV's HDMI2 slot. In particular, it is all about the order in which I put the devices into standby after watching TV. If I put the TV into standby first followed by the PVR, the TV is likely to re-boot the following morning.If on the other hand I put the PVR into standby first and then the TV there is no problem.

I have no idea why that would be the case - it just is.

I hope that others find this helpful.