I stumbled upon this thread while trying to open the port for transmission to operate in active mode.
Besides the possible firewall modification (on a fresh F32 install all ports are open by default), port forwarding (in case you are behind a router), transmission has a bug in its port checking mechanism.
On F32, transmission v3.0 is affected.
If you confirm that your port is indeed open on a site like canyouseeme.org then append this line to the /etc/hosts file:
87.98.162.88 portcheck.transmissionbt.com
This forces transmission to use IPv4. More details on the github issue page.