@terziyski Yes, this works. But this is not the final solution. If I would set it permanently in my network I would have other problems. So I have to live with 2,4GHz connection Thank you!

I have a FritzBox 7590 AX with 1200 AX repeater. The TP-Link router is in Client Mode. When doing a WiFi scan, it only finds 2,4GHz networks and his own 5GHz network. How can that be? Very strange...