Security issue blocking site access

[Q3]

Forum URL: Adamtopia.com

My custom URL expired. I paid to renew it but now I can't reach the forum with it on the Proboards URL. We are getting a security issue with the https/SLL certificate -- "Security Certificate Invalid". How can I fix this?

Thanks for the help.

Update: I can now get to the forum but only on MS Edge if I turn off all the security. 

[Q3]

This is now resolved. The update process just took a long time.