If your VPN connection suddenly stops working when you are using a Synology NAS with Synology VPN Server this may be caused by a few reasons.
- You have added a new certificate in Synology in Security -> Certificate. Check the Settings button to see what certificate is used for VPN server.
If my case, I am using a certificate issued by Synology for all services except for the VPN Server. If you added a new certificate and you are also using it for VPN Server, then you must go to VPN Server -> OpenVPN and click the Export Configuration button. This will give you a new config for your server.
Always check the exported configuration file for the correct IP and Port.
2. You are using the default certificate from Synology, but it expired and was renewd. This is my case.
In my case the certificate was renewed 2 days ago. Because it’s a new certificate you must go to VPN Server -> OpenVPN and click the Export Configuration button. This will give you a new config for your server.
Always check the exported configuration file for the correct IP and Port.