DSub network errors

[cee3]

I have 2 Android devices that use DSub (v. 5.5.1) to connect to my Airsonic app (running on Apache Tomcat 9) running on 2 different Windows computers, one Windows 10 and the other Windows 11. After using DSub for years it suddenly is giving me network error ("A network error occurred. Please check the server address or try again later.") when trying to connect. Server addresses are correct. This is happening on both Android devices (Galaxy Tab 8, Android 11; Galaxy S10, Android 12). I have tried clearing cache, clearing data, uninstalling/reinstalling the app, rebooting computers and Android devices, restarting router. Still get the error.

I can connect to these Windows computers using other apps from these Android devices (Splashtop, Solid Explorer for instance).

Any idea what's going on here?

[cee3]

It seems that the Windows Defender Firewall was preventing me from connecting. I am already using a 3rd party protection suite (McAfee). After turning Defender off (not easy as the enable/disable toggle did nothing; it wouldn't let me disable it), I was able to connect. To turn it off I had to go to the registry and disable it. To disable in registry:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MpsSvc\Start

"4" means disable.

"2" means auto.

Restart computer.