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Is it safe to downgrade WLC 4402 software from 6 to 5.1? My problm is the web autentication through IAS server dosn't work - can't pass the authentication login window,it works before on 5.1
I don't know about "safe" but there's a risk that you may/might loose your config after the downgrade. Take a copy of your config.
also controller 6.0 runs CAPWAP and 5.1, LWAPP, so you will have a downtime for your APs and it sounds like it will have to change the code on the APs as well. Sounds taking quite some risks here.
Thanks for your inputs.