Error code 2604

Good morning, 

I have been trying to get minecraft education to work for my students. We were able to play in December, but now everytime my students try to log on they get error code 2604.

- They work on chromebooks

-They use school accounts (WIth a schoolwide licence including minecraft education)

-They have tried different wifi networks

-In December it all worked fine, as far as I know nothing has changed. 

-I contacted our school's IT department but they could not find anything wrong on our end. (They also noted that no URL's were blocked)

-It does work on my regular laptop with my login

-My students are able to log into other applications using their microsoft credentials. 

-My students are able to login to the minecraft education website

What other things could i try to fix it?