We have started supporting T350C/D from version 6.0. Please upgrade to version 6.0 and apply below AP patch (18.104.22.168.1610) before registering an AP.
Unfortunately the controller vSZ (HS) we are using now is on the firmware version 22.214.171.124.302. The number of AP we have is about 2400. We have from ZF 7xxx, Rx00 to RX10 series. They are legacy devices and we have 70% of it.
For these devices we use AP firmware 126.96.36.199.695. We now that we can use a firmware n-2 and that is ours setup. And that's a big problem.
We don't now how to use clusters, and can we manage with clusters different firmware's.
Can we upgrade controller on 6 or higher and keep manageability on legacy AP working on AP firmware 3.6xxxx?
in SZ6 you can support a 5.2 zone, but not below. This could be an option. Upgrade your controller to 6 and the zones as well to be able to support the new T350 series.
If you have access points that won't work beyond 5.2 you could leave them in a separate zone. Though I don't believe there are any APs supported in 5.1 and not 5.2 should you should be able to upgrade no problem.
What is your concern to upgrade to 5.2? i.e. which access points do you believe are unsupported