My server appears to be listed fine on the server list, but players report that after pressing the connect button they can’t join because they’re presented with a message about whitelist in french, which my server doesn’t have. So it’s probably a message from a different server, ie people get redirected somehow.
Direct connect works fine.
The issue appears to have solved itself somehow. Sucks that it happened, it lasted over 6 hours during the time when the server is usually full.