Solution
Make sure that the certificates are updated. When you have the OPC UA certificate terminal empty. It will default to
Default OPC UA.der and these certificates are only read when the server starts so if your application runs continuously you may experience a similar behavior when trying to restart the server.
You can
create a new certificate with a different date to reload on your server and make sure that the dates are set to a time where you may be able to update the application or redeploy for maintenance.