I have a customer with R500 and R510 running unleashed Firmware 200.7. I added another Access Point R550 and I knew there is no firmware that supports R500 and R550. I thought it should be possible to have one unleashed system with all R500/510 and another system with the new R550. I knew I will have to perform all settings in both systems.
What I saw is that some R500 APs want to join the new R550, they are shown as "not supported" on the R550.
I also did set one of the R500 as preferred master on the R500/R510 whicht did not seem to stop some APs to try to join the R550.
Is there a best practice to run different unleashed systems in the same network? The next option I can think of is to create two different management VLANs on the switches but I hope there is an easier way.
The issue has gone for the moment. Maybe it took some APs a while to get the "preferred master" setting. In my setup, I have a preferred master set in the 200.7 unleashed system, but no preferred master set on the R550.