The message that you have is that the CRL has expired.
Presuming that you are running with CU186, there is a bug in that version.
Follow the instructions in this post and the CRL updater will work again.
https://community.ipfire.org/t/log-summary-openvpn-no-crl-update/11816/7
Make the green change shown in the link at the end of that post on the file /etc/fcron.daily/openvpn-crl-updater and then run that script with the command
/etc/fcron.daily/openvpn-crl-updater
and it will run that script and update your crl and the connection will work again.