3.6 is carrier code. forgive me for a working code without the fluff. Fluff = porn reference If there are no switches in your environment nor 750'd then for God sake don't upgrade. Trust someone that is into an 18 hr day and a promise of a patch comi...
Bino that depends and no. If you are on 5.2.1 then no you can not downgrade to 5.2.0. unless you have a back up (cluster restore)... 5.2.0 build 699 is what I would suggest unless you don't need the NMS. No NMS and no R750 in the latest code in 3.6
5.2.1 is NOT stable and has bugs. If you are running a captive portal wlan in your network there is a bug with the redirection using the AP certificate instead of the SZ cert and you will have to revert back to 5.2.0 or below to get it working again....