High Dpi second монитор leads to крах

I have Убунту Вили Werewolf (GNOME 3) installed on в Dell XPS 13, connected to в (relatively cheap) 4K монитор. I had huge issues with my стандарт resolution монитор (conflicts between the high resolution of the XPS and relatively lower resolution монитор); the 4K монитор was supposed to alleviate these issues, which it does...

... for about 30 minutes, after which the system inexplicably крах and шоу the login screen. There doesn't seem to be any excessive strain on the system, it just gives up for не apparent reason.

Ты существуешь anyone else had the same issue? Any tips on how to debug this?

Thanks