so everytime me or my friend places a port on a waterway, the person not hosting the server gets a desync error and is kicked. You can no longer join until the port is removed, and it kinda screws with us because we are playing on an island world. Any suggestions? something we are doing wrong?

not happening in my 18.6 heavily modded island world, can you give a mod list or save file or both?

Hey, thaks for the reply. Mods are:
Bottleneck
CanalBuilder
Cargo Ships
Endless rescources
Islands World
Squeak Through
- We also had Loader Redux, and Opteras Library, However we deleted them to see if it was the problem, as it was the only mod i could think of that could have had any effect. We didnt actually use the mod before deletion, however the loaders still appeared in the crafting menu after deleting the mod files. We are on factorio version 0.17.79. The port that was causing the problem was the one up near the oil pump jacks on the world (files below). Strangely, no other ports caused any issue, and i even deleted the one near the main base to see if it was a bug with more than 2 or more ports on a track. After switching server hosts with my friend, it worked for around 15 minutes before breaking again. Note, it only caused an issue for the person not hosting the server.
Save File: https://drive.google.com/open?id=1vd7xc6ASU_SPhG-sS14jdSz2eSU39M28
Thanks for Reading this :)

the desync stops after removing Cargo Ships, or, it stops by removing just the ports, or, you haven't been able to make it stop? sorry, wasn't clear there

it stops by removing that specific port next to the oil pumpjacks. Tried to delete then replace, but desync still occurs. Thanks

it stops by removing that specific port next to the oil pumpjacks. Tried to delete then replace, but desync still occurs. Thanks

unfortunately i can't be much help with this issue but i hope the clarified details help the mod author determine what's going on.

i would try removing the waterway and replacing that as well. any luck then?

Good news! we updated to 18.6 and problem is no longer occuring. I guess thats case closed!