Today I changed the url in the config.php file to:
'url' => 'https://www.mydomain.com/forum',
I basically added www
but It turns out that it doesn't work, displaying the typical error message: Something went wrong while trying to load the full version of this site.
That message is displayed when joining the website either with or without www.
I don't know if this helps but if I don't write the www in the config.php
and I join the website with the www everything works except from the icons