What is the Proper way to do an upgrade? Planning on Upgrading from 9.1.2 to 9.6.2. But i don't know if after backing up my config, i should do the upgrade while the APs are connected to it (online)... or whether i should down the ZD (offline), upgrade the ZD, then reconnect it back to the network, and hopefully all the APs will be upgraded...?
APs will upgrade/downgrade to whatever version your ZD is running. You can
disconnect the APs or ZD from the network when doing multiple version upgrades.
Check the last version Release Notes to be sure you follow the necessary ZD
firmware upgrade path.
Start all upgrades at Administer/Backup page, and save a copy of your current ZD
configuration. I recommend to add digits like '91208' to indicate the version that
they came from, if you need to restore config with a firmware downgrade.