Cannot connect to mongodb atlas through mongo shell

In my case reason was that provider changed my ip address (I have dynamic ip, behind NAT)

after I've updated ip whitelist, connection was restored

Actually the reason why I couldn't connect is because I had a network restriction from my university's wifi. I was given a test url http://portquiz.net:27017 from MongoDB's support team, I opened it in a browser and I couldn't access it. I changed to another place with wifi and it worked.

The new atlas ui - please note that for better security you should not use 0.0.0.0/0 nut your own ip address or use available timer to terminate the rule