When hosting a multiplayer session, a friend who connected found that changes to the game world were only reliable when my character (as the host) was stood close to his character (as the client).
If my character was a long way from his character he was frequently unable to connect belts or power lines to machines, or place new machines and foundactions. Once my character moved close to his this issue seemed to disappear, but it returned as soon as I moved close to him again.
Network quality was set to Ultra, and network latency was reported as being 10ms on both sides. Game is relatively early (Tier 4/5) and little has been constructed outside of the starting area (Grass Fields).
More detail available in Reddit thread: