I totally wasn’t aware that Discourse doesn’t really have any role based capabilities. I had only used it in projects so far where this wasn’t an issue. I thought it whould be possible to limit login through that.
@JimPas as @Stephen rightfully said that won’t work for the imported users.
DNS Name change will be in place for that period as the old forum will still continue to be live in that time but as I said initially I wanted to have additional protection.
Looks like http base auth will be the only way to put additional protection on it and keep users from logging in. I need to check how that works.
Thanks guys.