Hello, I connected my Android mobile and my computer with a usb cable and diabled the firewall on my computer. Then I tried to connect both via kdeconnect but the connection cannot be established. The android mobile says: "Das verbundene Gerät ist nicht erreichbar. Stellen Sie sicher, daß es mit demselben Netzwerk verbunden ist." (german) in english: "The connected system is not available. Please check that both systems are connected to the same network." But when I activate wlan on my fritzbox, then the connection works. I guess there is still something that blocks the connection of both systems via usb. I made a thread in the opensuseforum: https://forums.opensuse.org/showthread.php/526021-Erneute-Probleme-beim-Zugriff-auf-Android-Smartphone-via-MTP Thanks for your help.
Looks like you got a bit confused :P First of all, your firewall has nothing to do with the USB connection: it just blocks stuff coming from the network. Second, as you experienced, KDE Connect does nothing over USB: it only works over wifi. If you want for some reason to use a USB cable to transfer files, then you need to use MTP or something else. But hey, you have KDE Connect, so who needs cables anyway? :D