Oh no, this is embarrassing: I think I've finally found the problem and it has nothing to do with nostream. 🙈 It seems the main reason of my outages have been too low limits in my NGINX configuration (worker_connections & worker_rlimit_nofile). But thanks to your help I have improved swap and memory efficiency on the way. 🤙 I am 99% sure the problem is gone now. I'll wait some days and then document my findings in the issue and close it. Thanks for your help!