Revisit: Microsoft Teams Calendar through WAF

For all searching for this Problem with Teams not showing the calender app using hybrid szenario.

Refering to this basic guide:
Sophos UTM: Create WAF to allow traffic through Exchange 2016

using the MS Connection Tool:

https://testconnectivity.microsoft.com/tests/TeamsCalendarMissing/input

using a account with teams license (temporarily) active I ran the test and noticed that Entry URL /api/... was used.

So do 2 things:
Add "/api" as an Entry URL to the Exchange Webservice Firewall Profile

and add "/api/*" to the URL-Hardening exception.

Rerun the Test: all fine.

After 10-15 Minutes, customer restarts Teams correctly, the calender app is where it used to be.