To help troubleshoot, do the following
sudo systemctl stop firewalld
See if it works with the firewall disabled. If it works, do the following.
Open up the firewall app by right clicking on the firewall icon, then ‘Edit firewall settings’
First thing is to set the rules to ‘Permanent’. It usually ‘Runtime’ by default.
Then select the ‘upnp-client’ under the Services Tab.
Next, click on ‘Options’ in the top panel, and click ‘Reload Firewalld’
Reboot the computer and check.
Pudge