Connection lost

i run Mineos in a proxmox vm.
on my Server i run a modpack (all the mods 6)
i connect over lan and 2 friends over internet
we all 3 get a error after random time (5min-2h) but all on the same time:
connection lost
internal exception: Eine vorhandene Verbindung wurde vom Remotehost geschlossen.

a few seconds before the error the interface say: waiting for server…

the server is still running and shows no logs just
[19Apr2021 14:23:41.160] [Server thread/INFO] []: DangerDragon3295 lost connection: Disconnected
[19Apr2021 14:23:41.160] [Server thread/INFO] [net.minecraft.server.dedicated.DedicatedServer/]: DangerDragon3295 left the game

Sorry for my bad english and greetings from Germany

Are all 3 connections using the external IP address? Any other devices lose connection at your location?

I use the internal ip of the server (
For the other guys I use dyndns from Strato over my Fritzbox.
Other devices work normal.

Hey Rene,
Old topic, but did you ever solve this? Im having exactly the same problem, also running from Proxmox

Thank you!!