Question: Tuta mail app not working at place of work

When I'm at my place of work, where there is wifi available, my tuta mail app will not work. It goes offline, and I can't reconnect anymore. So I figured maybe it's something with the wifi, but when I disconnect and use regular data, I still can't get back online.
When I get home, it works again. Both on wifi and regular data.

Can anyone tell what's going on? I need to be able to recieve mails while I'm at work.

Best regards