You have a new Microsoft Teams Room system and there is a burple banner at the top saying Couldn’t sign in to Microsoft Teams. What could the problem be? Well, the first thing to check is that the account does not have Multi-Factor Authentication available (MFA). In the video below I show you how to check this. It’s very straight forward.
Always do this from the actual MTR device, as this will prove off that the network switch, VLAN, etc is routing correctly. Browse to the desktop side of the MTR and then open a browser to Microsoft Teams. Then login with the room resource account. If you are presented with any additional pop-ups, then there is your problem. MFA must be disabled and use Modern Authentication instead. Modern Authentication requires version 126.96.36.199 or higher on the Microsoft Teams Room app.
So that is one stop for troubleshooting sign in issues with your MTR.
The other way to test is browse to Outlook Online and then login and test the calendar to ensure you can see that.
Hopefully these tips will assist with the Couldn’t sign in to Microsoft Teams error that you may se on the devices.