Comment # 1 on bug 996837 from Alexander Bergmann

By default all interfaces that are not assigned are treated as external zone
interfaces. So only explicitly opened ports are available for connection.

If you put your eth0 into the internal zone, it's like to switch off the
firewall completely for this interface.

The right way to go here would be to open the necessary ports for KDEConnect
for the external zone. It looks like TCP and UPD port range 1714-1764 is
needed.

https://community.kde.org/KDEConnect

Create the following service file

#> cat /etc/sysconfig/SuSEfirewall2.d/services/KDEConnect
## Name: KDEConnect
## Description: Allow access via KDEConnect
TCP="1714:1764"
UDP="1714:1764"

and add KDEConnect to the allowed services on the External Zone via

#> yast firewall


Closing this bug as INVALID.