This article explains the "lonely mode" feature on Datto Networking products.
If four Internet checks in a row fail, a node in repeater mode will fall back into 'lonely mode'. The node assumes that it operates on a wrong WiFi channel (the channel might have been changed).
In lonely mode, the node turns itself into a wifi client and scans through all channels in the hope to find an internet connection somewhere else. Scanning all channels takes roughly 5-6 minutes.
The WiFi LED will blink red when a node is in this state.
Note: In this mode normal WiFi operations are disabled; otherwise the node would not be able to scan and switch channels.