As far as I’m aware, the main flex daemon, lmgrd, will attempt to listen on port 27000. Our vendor daemon, pgroupd, will randomly pick a port between 1024 and 65535. You can force pgroupd to use a particular port by specifying it in the license file by writing PORT=<port-#> after pgroupd on the second line, e.g.:
SERVER <host-name-here> <host-id-here> 27000
DAEMON pgroupd PORT=12345
Depending on how you’ve configured the network, you might need to make an exception to allow those ports through. Something like the following will add the appropriate exception:
$ sudo iptables -A OUTPUT -p tcp -m multiport --dports 27000,12345 -m conntrack --ctstate ESTABLISHED -j ACCEPT
$ sudo iptables -A INPUT -p tcp -m multiport --dports 27000,12345 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
My first suggestions would be to temporarily disable the firewall first and see if you can get the two to connect, just to isolate the issue. You can also prepend FLEXLM_DIAGNOSTICS=3 to compilation commands to see how the license is being checked out.