Change from Port 4433 to 443 and 808 to 80

Operating system and version (eg, Ubuntu 20.04): Raspbian GNU/Linux 10. 5.10.63-v7l+ (armv7l)


currently I have the nextcloud configured to listen to port 4433. In the I rerouted port 443 to port 4433. Once I set that system up I managed anyhow to get letsencrypt running. Saying this, my certificate expires in a couple of days and the renew process via nextcloudPi isn’t working any more

OK, I searched the internet and found out that using not the standard ports with nextcloud makes problems. I can acknowledge this, since displaying the system info it says that port 443 (and 80 as well) is closed although they are opened in the and routed correctly.

Now I want to reconfigure the nextcloud to listen to 443 instead of 4433. How can I do this (Note that I am not very experienced)? Thanks for your help in advance.