When a new copy of freepbx was installed by booting from ISO, I went to the IP address shown after the console login and set admin user name and password. Next, I clicked on the admin link and got “problem loading page, unable to connect”. There is nothing in the browser development tools network tab. From the console, my VM host’s virtual address pings, my LAN addresses ping, but the freepbx IP address does not ping from the LAN.
ip addr show and route on the console are normal.
Having installed lynx, I went to localhost and got the login page, so it is only inaccessible from the outside.
How should I regain access to the admin UI?
FreePBX’s initial config script uses a wrong netmask on the trusted network. Whereas the netmask should be 8 you set it to 24. This is not going to work.
Restart twice within 5 mins. This temporarily disables the firewall. Then fix your firewall config
The point is that this math is wrong:
Wrong netmask is calculated during the initial set up, and it bars the admin from the admin UI.
And then this begins to rain:
Not very encouraging.
Mildly annoying, maybe 
Looks like bug in OOBE.class.php portion of the firewall module – added new issue #730 in GitHub to track this.