It is definitely the server end.
The issue also stopping the IOS app working... just says "Band internet connection"
Other users in the organization are having the same issue. tried multiple machines and multiple internet service providers and same issue. I have now opened a case with support 06827732 and sent them the Crome .har file you can clearly see the 40 Second delay with the cloud responding to login.
If you are having the same issue can you mention the country you are in.