Just to return to this for a last time:
I have connected the printer to the router by the USB port. The printer is connected to the wifi network wih the IP address 192.168.187.43. So both the PC and the printer are directly connected to the same network. Printer Information Report says connected to the network, IP address as above, signal strength is excellent, connected to internet.
Run hp-setup and hp-setup 192.168.178.43. No printer detected. Yast, CUPS no printer detected. HP Smart app shows the printer but not available.
I think it’s time to give up!