Yah, you are right, I tried to search using google, but haven’t tried the forum’s one, since wasn’t really sure how to ask the question correctly.
Anyways, thank you for your answer, it partly fixed the problem, and then on a suggested thread I found also an additional note, so will post here a full solution which worked for me:
1 - Change the /etc/apache2/apache2.conf contents to this:
(source: the one recomended by @Raphael)
2 - In same directory /etc/apache2/ there should be a ports.conf file and a ports.conf.XXXX.
Make a backup of ports.conf file, then delete it and rename the ports.conf.XXXXX to ports.conf
(source: Apache2 broken after upgrade - #5 by eris)
3 - sudo systemctl restart apache2
4 - it now should work as expected 