Moving up and down platform works however it makes my character try to noclip anyway to fix this?

Also, sometimes it is fighting with itself whether to set the owner to the server or the closest player. happened to me a lot, and SetNetworkOwner() was the solution for me.

No, they’re using a tween.

The velocity is set presumably as an attempt to fix the problem in the question.

yeah sorry i wasnt here i had to go do somethin anyways whats going on?

The problem you are experiencing is because of latency - the physics updates have to travel from the server to the client, which takes time. If you were to do this on the client, it wouldn’t be nearly as jittery.