When i turn on a moving part i phase through the blocks, but on the sever my friends move just fine.

This issue has been marked as stale because it has been inactive for 3 weeks. It will be closed if it remains inactive for another 3 weeks.

This issue has been closed since it has been inactive for 3 weeks since it was marked as stale.

known optifine issue

Several Optifine versions on 1.16.x may cause client crashes or lack of collision within Create.
If you find yourself having one of these issues, update Optifine to version 1.16.5_HD_U_G6.
This version has no such problems, and is compatible with both 1.16.4 and .5. Cheers!