Hi,

From lack of any response, I understand nobody had this problem before me :-)
I managed to resolve it with the help of a friend who asked around. I would like to post it here so that if it happens to anyone else, it might be helpful:

1- I had upgraded my OS v'a HowToForge guides. They are excellent. I had followed the following guides in the order given below:

1- https://www.howtoforge.com/how-to-upgrade-from-debian-10-to-debian-11/
2- https://www.howtoforge.com/update-the-ispconfig-perfect-server-from-debian-10-to-debian-11/
3- https://www.howtoforge.com/ispconfig-php-debian/

The suspicion was the problem was due to something may have gone wrong in the 3rd step, that is; ISConfig upgrade. That ISPConfig upgrade also reconfigures any postfix, dovecot, amavis, spamassassin settings which may have been overridden by the Debian OS upgrade.

So; I guess the first time I did the ISPConfig Upgrade, I might have overlooked something due to the fatigue of taking all those backups, OS upgrade etc etc and may not have noticed a warning/error message. Anyways, when I simply rerun the ISPConfig upgrade, it resolved all the issues!

Note: In my many hours of trying to resolve this problem, I have resorted to the help of Chatgpt and Deepseek. Out of my experience, they are very usefull as reference tools but DO NOT USE THEM as experts or nor your colleagues! They come out very self-assured and wrong. They even give false promises like `we will sort it %100 this time` kind of BS.. Also when you point to the mistakes, it is amazing how quickly they accept it propose the completely opposite idea with the same level of self assuredness:-)

Continue having fun with Elgg!

Take care.