I got the folllowing error after building pipes for the first time (not sure what exactly caused it, unfortunately I have many mods). Despite this being non-fatal, I suspect it causes desyncs so this is actually a blocking bug.

Stack trace:

https://imgur.com/n0Z18Jh

Interestingly I was playing multiplayer at the time and my friend didn't desync right away. But then, we saved and quit the game, then reloaded, and now he immediatly desyncs when trying to join

Could you try updating RFP to 1.7.6 or newer? It should've been fixed in that version.

Thanks. I gave a quick test and it seems to be fixed with 1.7.6 (although I didn't play for long after that, just made a test to help you debug).