Very strange behaviour of Network Admin Urls

Hello to all!
I’experiencing what is in the topic. Let me explain more in depth.
I have recently migrate a directory based multisite installation from one domain to another.
Originally, WordPress was installed in its own directory (following wordpress official guides).
In the new domain I gave at the new directory the same name as the previuos installation, only domain as changed (that has letsencrypt SSL certificate). Following the “moving wordpress multisite”, obviously, I’ve changed every references to the old domain with the new one in the database (with https://www.mynewdomain.com).
Wp.config.php and .htaccess as the same as the original. Wp-config received propers update with database infos and domain url.
So, I’ve got problems on the Network admin menu URLs.
The entire front-end works well, but the Network Admin URL menu does not add in its own urls the “www”, resulting in https://mynewdomain.com/wp-admin/network/ instead of having https://www.mynewdomain.com/wp-admin/network/. So I have to add it manually, also when updating plugins to complete the script. The rest of dashboards (main site and others) works perfectly. Only the “network” area seems broken.
Read many many posts, did many searches with no results.
Thank you,
David