Mulitplayer issues

[CabinetGuy]

Good Evening, everyone!
My brother and I play every weekend, and the last few months we have been experiencing MANY disconnects during the game.
It is not consistent. Sometimes it tells him that I disconnected, other times I am told that he did. Neither of us are disconnecting, of course.
Is there a way to use ZeroTier and LAN play, and avoid using the official servers?

And yes, we have tried every troubleshooting step we could think of, to no avail.