I made a few changes after running into errors I listed above for Debian 10.
As of now, it seems Debian 10 is fully functioning now.
If anyone wants to give it a try for Debian 10:
wget https://raw.githubusercontent.com/tcreek/astpp_installer/main/astpp_v5_install.sh
Debian 11 is still not resolved. As previously mentioned, the major difference between Debian 10 and 11 is PHP v7.3 vs PHP v7.4,
Since the error is coming from the ASTPP code (source listed above), maybe you can provide some input on what sort of issues would cause the ASTPP code to throw errors?
Remember, this script only uses Debian repos, and source code available from SignalWire’s FreeSwitch, and iNetrix’s ASTPP. This way, there is no need for a SignalWire token, MySQL repos, nor Remi Repo.