So I think I’m running into this problem a bit now. The reverse proxy and everything TCP and HTTPS works. The mail server I’m still trying to figure out. I’m using Wireguard to tunnel, do you know how to “bridge” that up to the VPS so that ports I need open to listen for incoming SMTP are also being listened on on the VPS?

This is the solution I went with. Had to tinker a bit with the KeepAlive settings, but otherwise smooth sailing now! Thanks!