Hi Dimitri,
The command I provided is an AP CLI command. You need to connect to the AP using SSH (port 22) to run AP CLI commands.
If you cannot access the AP - then this may be your problem - you may have network connectivity issues to those AP's so they are only able to connect via MESH.
If the MESH connection is actually working you should still be able to SSH to the AP and run some commands to verify the AP operation.
Some other troubleshooting commands from the AP:
get eth
get ipaddr wan
get netstats eth0 (assumes AP is using eth0/LAN1 as wired connection)
get mesh
get director
I suggest you check the physical connections to the AP, check if there is link integrity LED's on the Ethernet ports and switch ports, check the switch if it detects the AP.
I hope some of these suggestions lead you to a solution.
Thanks