OpenVPN client reports password error and only connects after restarting Nethserver

Hello everyone, I use Nethsserver 7.9.2009 and it has the VPN and file server with active AD and VPN users are registered in AD and eventually I have a problem with the VPN password where the OpenVpn client accuses password error and after I restart the Nethserver it connects again, I would like some information about this problem.

Please check /var/log/openvpn/openvpn.log for errors.

Do you use fail2ban or IPS? Maybe it blocks openvpn somehow?
Which OpenVPN client do you use?
Does it affect all users or just one?

Is the error reproducible or did it occur just once?