DIAGNOSIS The device is in setup mode but cannot authenticate with your router. Usually a 2.4 GHz vs. 5 GHz band issue or a password error.
FIX Power cycle your router and the Echo Dot. In the Alexa app, forget the device and restart setup. Ensure your phone is connected to the 2.4 GHz band of your Wi-Fi. Enter the Wi-Fi password manually, checking for case sensitivity.
IF THAT DIDN'T WORK Your router may have a setting like AP isolation or a firewall blocking the connection. Temporarily disable these features for setup. For mesh systems, try connecting to the primary node's network.
HEADS UP The Echo Dot 5th Gen does not support enterprise or WPA3-only networks. It requires a standard WPA2 personal network.