Wireguard stops working

I am running the latest DIETPI software on a Raspi 4.

Some month ago I set up Wireguard and war rather proud to have my own VPN now. I only used it to use my home Internet connection, when I am abroad.

Since a while it doesn´t work anymore. And I have no idea where I should look and how I should start looking for a Failure.

Is there a kind of checklist I can through?
Many thanks in advance

Check if your DDNS is setup correctly and pointing to correct external IP address. As well check your port forwarding. On your client, you should be able to check VPN logs within the WireGuard client app. On server side, you can use wg command to verify successful handshake. by designe, WireGuard don’t have any logs on server side.