crashes at single location please help

So I’ve just built our new intranet site, everything was working perfectly until I rolled it out to everyone. When they started logging in the whole thing froze and would ‘time out’ server not responding’ ‘server sent no data’ – I have multiple sites running on the server and no others went down just the new intranet.

It stays down for half an hour and then again when a few people try and use it the whole thing goes down again.

Is there some kind of restriction? (I have not outguns downloaded to do this by the way) but a restriction of the number of logins from a particular ip?? As we are in an office it’s a static ip and maybe that’s the issue as I can access the site perfectly from my home remotely. Very weird and don’t know how to resolve it!!!