There's gotta be something less common about your installs that is triggering this instability. Have you raised a ticket with support?

I agree things have gone downhill with the 4.4.x release family onwards. More bugs, more issues and delayed updates.

Personally, my 2865ac has been stable throughout the 4.4.5.x releases though.

Hi have been in touch with Draytek support about my router 2865 which has been having major issues since April this year.
The major issue was that the router would at random not enable certain LAN ports at all.
I would say that the support had no clue what was going on. Not helpful at all. In total, very bad experience.

I too am wondering what it is that makes some configurations appear less stable.
I wonder what needs to be configured to trigger instability?