The issue seem to be depending on want Akamai server the DNS resolver send you to, the default DNS server for my isp return ip's for a Akamai server that Avast forum actual works on CF,Quad9,Google,Opendns,Nextdns all return different IP none work.
The funny thing is on Akamai server that Avast forum is broken on, static assets still load on it e.g.
https://forum.avast.com/avast-forum.png.
Anyone using Nextdns/Adguard home or similar that supports DNS rewrites if you rely need to get on Avast forums and don't want to use vpn/proxy or switch to other dns server you can get it working by overwriting the DNS to return a ip of a working Akamai server.
Here two Akamai server that Avast forums works on.
23.197.207.144 Sweden
23.198.214.202 New York (USA)