I configured the R600 as the Master AP and wanted the R500 to be joined.
After upgrading the firmware to 200.1.9.12.55 it was found by the
Unleashed network, but it's permanently disconnected. I made a special
subnet for this case: 192.168.64.0...
Thank you for the help, it was the firmware. For some reason I found only the .55 yesterday and not the .62. Now both APs have the newest firmware and its finally working