The fact all your friends can join the server just fine and you can not is odd.
The error you show also usually indicates the server its self is offline.
Try to reproduce, and look at console, the errors will be there. Download latest.log
Home > logs > latest.log
Upload it here so I can check it. Additionally, make sure you're accessing the proper account you had those servers on. If they refuse to appear, and you are certain it is the right account even through enabling cookies, using a different browser, and restarting your browser, you will need to make a ticket here: https://minehut.zendesk.com/hc/en-us/requests/new?ticket_form_id=4999999402643