samtto One of website domain names was blocked by the IT firewall, I can not solve, so I had to add a domain name for flarum.
GreXXL From what I understand so far you want to change the domain to another one rather than use both at the same time? You can change the domain your installation uses in the config.php. Another option you have is redirecting the old domain to your new domain.
JohnP If it's just for internal communication, can't you just redirect one domain name to the other at a DNS or htaccess level and then just use one domain name for the actual Flarum install?