WireGuard not reachable all of a sudden?

I think this “DequeueBuffer time out” is something else.
So no handshake happened, so my guess is the address for the endpoint is wrong or the endpoint is not reachable for some reason.
For the sake of completness:

  • The wireguard port is forwarded?
  • Is the format for the endpoint address correct? (domain:port or public_IP:port)
  • If you use a DDNS: Did your IP change recently and the DDNS still has the old one?

For testing you could change the endpoint adress to the local IP and test from within your LAN if you can connect. (to rule out problems with the wireguard config)

As well you could use your external IP address instead of DDNS name inside your client app configuration to exclude issues on that level. One more thing would be to remove and recreate port forwarding within your F!B