I realized when i was playing with my friends on a server that for some reason i couldn't enter The UI of a Train Station.

But when i tried to recreate the bug in singleplayer it was fine.

Also there was some desyncing problems with trains in my game when playing on the server.

Is there any way to fix this?

Somehow going into the ops.json file of the server fixed it.

huh? i've got the exact same issue, and it isnt fixed when looking in the ops.json file... i dont think you fixed it with that, it had to be something else