I called tmobile home internet support. They removed my physical home address where modem is located and added it back on. That resetted some sort of connection. Now my office worked. This was after my IT team repaired, then uninstalled and re-installed Office 365, current office version is 2208. 

https://connectivity.office.com I found this link via the Microsoft article. 

The Microsoft 365 network connectivity principles article might help. 

I don't have a firm answer to this behavior but I suspect it is related to the TCP or UDP ports used. The client will attempt to establish the session with the cloud server and if the ports are blocked that is likely the reason for the failure. Analysis of a packet capture with Wireshark would provide clarity. Of course that takes an understanding of the process. I decided to move away from the Microsoft solution and have gone with Linux and open source software so I have not been using Office 365. There might be some conversation on Reddit about this. 

same here. i am having issues with all my office 365 applications. 

The issue occurs on desktop on Outlook 365. Also on Outlook on web and mail app on iOS. No messages receiving/sending. Does not happen when off TMobile network.

You might want to be a bit more specific. We use a version prior to Office 365 and it works fine.

• Outlook 2016 for Windows and Mac. ... 
• Outlook on the web. ... 
• Outlook.com. ... 
• Outlook for iOS and Android. ... 
• Mail and Calendar for Windows 10.