You can’t the easy way would be to assign the user at the troubled client the same UID as on the server, change their files on the client to be owned by the new UID and hope it dosn’t inflict with any other users on that client.

The more problematic way would be to change UID of the user on the server aswell as on all the clients that are showing no error to represent the UID on the troubled client.

And the completely stupid way, make a new strategy of what UID every user should have, convert every client/server to follow this new strategy and hope nothing goes wrong with this comprehensive change.