STAS not working after I upgraded AD from Windows 2012 to Windows 2019

Check if your AD connection is broken ...  at Authentication / Servers.

Possible you have to switch to SSL/TLS.

How do I check the AD connection is broken? I also tried to switch to SSL/TLS but the connection was unsuccessful.

Hi Euston and welcome to the UTM Community!

In 'Definitions & Users >> Authentication Services' on the 'Servers' tab, open each of the new server definitions and 'Test server settings'.  If that works, re-join the domain on the 'Single Sign-On' tab.

Any luck with that?

Cheers - Bob

Thanks BAlfson, but see the screenshort if I put SSL/TLS. With plain text the test connection is sucessful.

Possible you get more answers within Sophos XG community...

https://community.sophos.com/sophos-xg-firewall/

Euston Kazembe :

 Sophos XG firewall: Best practice for STAS: Please refer the URL : https://community.sophos.com/sophos-xg-firewall/f/recommended-reads/125318/sophos-xg-firewall-best-practice-for-stas

Ahhh - XG, not UTM.  I've moved this thread to the XG Firewall Community.

Cheers - Bob

I managed to connect with SSL/TLS by following the link shared but still the STAS doesn't authenticate