Nginx and/or OPNsense UI unavailable after some time

[tz-mbc]

Hi there, is anyone here running OPNsense on a Hetzner CX… VM ?
For a couple of weeks I am dealing with a highly unstable setup which will fail within hours or sometimes days.
What I need is OPNsense+ReverseProxy with CrowdSec and Wireguard to support the service. I meanwhile got rid of Crowdsec and Wireguard to limit the moving parts but still, nginx or sometimes the OPNsense UI will freeze after some time.

When things go bad I can still get to the console and here's what I noticed:
Sometimes there's the following error: "Listen queue overflow: 193 already in queue awaiting acceptance"
I have found several entries in this forum, suggesting to turn off IPV6. But unless I forgot a v6 setting somewhere, it didn't help.

I tried to restart nginx via service nginx stop/restart but usually this will just show the process id and get stuck.

The only way to get the service back is to reboot. But reboots often get stuck as well because not all services will stop, might be the same nginx service. The console will then show this error: "some processes would not die, ps axl advised" and stay there until I do a power cycle.

With a physical machine I would start to consider hardware or compatibility issues, but a VM from a large hoster?

Edit:
After having been close to abandon this project I decided to start all over with a new VM. Well, what can I say, new VM, restored backup from faulty VM and got a stable running system with nginx+wireguard+CrowdSec active.
I don't know what issue the first VM had but whatever it was is gone now…