Hi Anthony,
For additional context other than the generic 'turn it off and on again' fix, there may be some other scenarios, common or otherwise, that can generate auth related errors.
* If you are using systemctl to enable the service, ensure that the user who configured the endpoint is the same uid that is running it. ie. Not running the systemd service as root while the endpoint was created/logged in using your own credentials.
* That this is a single user, not multi-user endpoint. The latter should mostly be run as root, as running as a non-privileged user is a special case
* The endpoint was not intended to run using a Client ID/Secret, which is the normal recommendation to avoid credential timeout
If none of these apply and the issue persists, then I suggest creating an official support ticket so we can look into your diagnostic logs to find the actual cause.
Lei