WHMCS admin login and front pages not loading ERR_TIMED_OUT

[Alex M]

Hi there 

Been experiencing a strange issue with our WHMCS program.  Nothing has been changed or updated recently, however as of yesterday, when trying to log in to our admin login (using Chrome browser and Edge / IE) I get an error when trying to load the admin page.  This error is also received when trying to load the front end pages such as the carts, knowledge base etc.   These pages were still loading in Firefox yesterday and were working for about an hour this morning, but now Firefox is also giving a time out message and not loading the pages.  

Chrome error: ERR_TIMED_OUT

Firefox Error: The server at www.mydomain.com is taking too long to respond.

Troubleshooting I've done so far: 

Used SSL checker to diagnose any issues - SSL cert is working 100%

Tried logging in with just http - still doesn't work 

Cleared Browser cache multiple times - Still not working 

Tried connecting from different devices, same issue. 

Tried connecting with different internet connections, still timing out. 

 

Has anyone else had this issue?  Any advice on what I can try further?

Thanks for your time