DIAGNOSIS The main Deco is offline. A flashing blue LED on a satellite unit means it lost its connection to the primary Deco node.
FIX Power cycle the main Deco unit plugged into your modem. Unplug it for 30 seconds. Plug it back in and wait for a solid white light. The satellite units should reconnect automatically, turning solid blue.
IF THAT DIDN'T WORK The satellite unit may be too far or has wireless interference. Temporarily place it within 10 feet of the main unit. Use the Deco app, tap the problem unit, and select 'Reboot'. Let it re-establish a fresh connection.
HEADS UP The connection between nodes is on the 6 GHz backhaul band by default. Physical obstructions like thick walls or large metal objects can severely disrupt it. Wired backhaul with Ethernet cables is the most reliable fix.