I don’t know if this has anything to do with the problem. Previously, I copied files from the NAS to /home/uli so the network card obviously worked - only it didn’t connect to the internet because there was no default gateway configured. In Yast -> Hardware I found under the network card driver the “modprobe r8169”. I was not sure if the module was loaded and just entered (as root) modprobe r8169. lsmod showed that the module was loaded. Now after the command rcwicked restart the network connected to the internet.