Outlook mail on Android phone via VPN connection does not work

Laszlo

HI!

I need help to use outlook mail on a mobile phone, which is on a local exchange server.

I can connect via VPN but when I set up the email account it gives a login error.

It works on other mail clients but not with outlook. 

Web outlook is disabled on the server for security reasons.

Firewall: TZ570

Exchange 2016

Android 9

Thank you!