Did you change something recently? It seems your domain can’t resolve to an IP and has issues with nameservers.
Not an expert. Ensure you use the right nameservers and your DNS entries look good (without duplicate). 
EDIT; It looks like you fixed the domain! 
EDIT2: Unfortunately, you have some trouble with theme components or plugins, feel free to use the safe mode if you need access to your forum (it works for me).