I tried using Wireguard on a Ubuntu LXC container in Proxmox. The handshake does not fail but is very unstable. If I connect to the server there can be multiple seconds until the handshake completes. After that, and that is a no-go for me, there seems to be a scheduled re-handshake after two minutes which just doesn't seem to work as ist should. Sometimes it can take up to 30 (!) seconds until the handshake finally succeed.
If I use Wireguard through my OPNsense firewall on the same local server, there is no problem like this at all (handshake in milliseconds). I tried using a VM instead of a container with Wireguard and it gets a little better but the problem still persists. Is this a Proxmox problem? Or an Ubuntu problem? Is there a way to fix it?
I used the normal Wireguard "apt" installation with wg-quick to set it up. The Proxmox server is locally in my Home but my router doesn't seem to be overwhelmed (this problem exist just using ping). Maybe someone can help me. If you need more information or context just ask.