Device connection failure

What should be done when error codes 135, 205800 occur during device network configuration?

What should I do if the device only connects to the 2.4G WiFi band and fails to connect to the 5G WiFi band?

Why only use AP mode (blink slowly) can add device successfully, but EZ mode (Blink Quickly) does not work?

When adding a Zigbee sub-device, the message "Unauthorized, unable to add" appears, and the gateway cannot find the device. What should I do?

How to troubleshoot if Wi-Fi device fails to connect successfully?

Why the device failed to connect (Bluetooth)?

What should I do when my device fails to connect to the network?

Why the device failed to connect (Zigbee)?

Why does App fail to add devices by Auto Scan?

How to deal with issues with distribution network after Apple system is upgraded to iOS 13?