There are many reasons as to why your server might not start. Some often issue people have is getting “cannot connect to fallback server”, this error message usually means that your server hasn’t fully started yet. If you wait 5 minutes and try joining and you still can’t then there might be an issue internally with your server.
We suggest that, if you still can’t connect to your server, that you start the server up, don’t join it, then go to the danger zone section of the panel and click “Repair Files”, this will hopefully resolve any plugins which might not have loaded correctly and are stopping you from connecting.
If you still cannot connect to your server we suggest you get the latest logs through the panel and put them in a Pastebin, once you have the logs create a support ticket and include a link to the Pastebin logs. They should hopefully be able to resolve the remaining issues.