NFS authenticated on server but denied on client

Environment - Debian Lenny GNU/Linux

Debian Lenny is used on server and part of impacted clients, but simillar problem was reported on other systems too.

Symptoms - client offline, server seem ok

Mount nfs fails on client saying reason given by server: Permission denied, while everything seems running okay, server has rpc.mountd: authenticated mount request from X.X.X.X in logs.. Reboot of client did not help, manual restart of services also not.

Solution - restart NFS server services

I restarted nfs-comon and nfs-kernel-server on serverside and everything works as it should. So the whole problem is something rotten in nfs server, next time, I will not wait that long to restart services on it in such case.

Notes - how to find this

I was not succesful fast in finding this, even the problem itself reported by others. So I made up this page and link it back and forth with usefull forum post on this: NFS mount fails, permission denied, authenticated successfully.