currently I work as a holiday replacement for our sysadmin and found out that the host certificate expired two days ago. Is it possible to renew the certificate without having to reconfigure everything from scratch again?
If the host certificate is renewed then all the client certs would need to be renewed.
Do you really mean the OpenVPN Host certificate.
I just checked mine on my vm system and both the Root and Host certificates were created in 2024 and the expiry date is 4762.
This shows the Host certificate.
The client certs have an expiry date dependent on the time period defined when the cert was created and the default value is 730 days, so two years.
The OpenVPN Clients table should have shown that the client certificate was due to expire in a short while if it is the Client Certs that have expired.
The following screenshot shows the yellow highlight and the (Expires Soon) message for the middle Roadwarrior client connection. The Expires Soon message starts being shown when the cert is 30 days away from expiring. Once the cert has expired then the message changes to Expired.