!..GAME BREAKING BUG..!

I spawn in and where i spawn in my player stays there for the entire time i am on the server, even though i am moving around and no longer in that position. my friends see me were i spawned in but my client position is invisible to them.. i can punch them and deal damage to them but they cannot hurt me unless they hit the version of me that they can see which is the one were i logged in. We are playing on a private shard server.. multiple of my friends are having the same issue..