Hi  @dononeil 

Your SDN devices (gateway routers, switches, or EAP) may have lost contact with the controller if your controller log is filled with messages stating that they are often disconnecting and reconnecting. The following procedures can be used to verify that the controller and SDN devices are connected, even while the internet is unaffected:

    1) Examine the quality of the wire that is plugged into the controller and the EAP units;

    2) Examine the controller's hardware;

    3) Replace the controller's power source to ensure a steady power supply;

    4) Update the firmware version to the latest.

Explanation of Isolated: (For APs in the mesh network only) The AP once managed by the controller via a wireless connection now cannot reach the gateway.

You can rebuild the mesh network by connecting it to an AP in the Connected status, then the isolated AP will turn into a connected one.

If you get "Failed to link to uplink AP" when configuring mesh, you may refer to the following steps:

    1) Make sure both uplink EAP and downlink EAP support Mesh function;

    2) Check if the Mesh option (Site view > Settings > Site > Wireless Features > Mesh) is enabled;

    3) Change the channel of the uplink EAP, please test on different channels;

    4) Move the Mesh EAP closer to the uplink EAP;

    5) Avoid obstacles and wireless interference between the uplink EAP and mesh EAP;

    6) Choose different uplink EAP units.

  @Vincent-TP 

I understand the basics, but the issue here is that vital information, like interface errors, timeouts, etc... are not being provided in the logs or through the interface. I could spend all day replacing cables, swapping ports, replacing switches, replacing power supplies, etc... but I'm doing this all blind without basic information about the quality of the links (ethernet and wireless). RSSI doesn't tell me anything about interference, 'Connected via Ethernet' doesn't tell me anything about the quality of the connection, etc.... Telling me "EAP225  was isolated" is useless.... I need to know WHY it was isolated. Was there a hello/management packet lost? Was it re-tried? How many times? What was the route the packet tried to take? etc....

We need to have more data available to us to really be able to debug an installation.

Right now the only thing of any value presented to me are the Ethernet stats, and that shows 0 TX and RX errors.... which tells me that the cabling to the AP is fine from the Switch, but I have NO interface stats from the uplink AP (this is connected via Ethernet to another AP, via a switch), so I can't tell if that cable is good/bad, or if the switch is the problem.... 

Additionally, I have no access to any interface stats on the controller, or the router that are both being managed (we're not using a managed switch), so I can't debug the phy on those things without just swapping them out.

We really need to have access to all of this type of information (dropped packets, interface errors, CAM tables, routing tables, etc...) on all physical and wireless interfaces so that we can debug weird situations like this.