i am facing issue with AP device showing offline (3K Plus device) in controller, but in real time AP are able to ping and also from web able to access, we check from CLI mode reachability to AP from controller and vise versa.
Recent we upgrade controller version from 2.4.1 ver to 3.1.1 ver on premises, it second time we face this issue at different location. But after degrade to 2.4.1 is working fine. AP are showing online in controller. But i need to check root cause for it.
can someone guide me to find out what was the issue.
Are you using DHCP to assign addresses to your APs? I found that whilst they would take the IP/default gateway, they did not appear to have a DNS address. The only way to fix it appeared to set a DNS manually. The easiest way of doing that was to set that in cnMaestro first. Then you set DNS manually in the AP. It then connects to cnMaestro, does a sync and all is sorted. It a really odd one, as they should recieve DNS from DHCP.