Going to do some scary things I don’t understand again. (SSL & domain stuff)
So if you can’t reach the forum, please use

Let me know if I can help.

Thank you! Seems like I could change the nameserver for the forum subdomain and the main site separately so the forum is unaffected.

Seems like I was wrong and the forum cannot be reached by at least some people even though the IP seems to have propagated. Can’t access by entering IP in Firefox and Edge either. Only tor seems to work. Tried flushing DNS record in os and browser.
I changed the nameserver back and hope it just takes a bit of time until everything is back to normal.