DIAGNOSIS This is usually a router compatibility issue, specifically with the 2.4GHz network band. The robot does not connect to 5GHz networks, and some modern routers combine both bands under one name (dual-band SSID), which confuses it.
FIX 1) Go into your router's settings (often via a web browser) and temporarily create a separate, dedicated 2.4GHz network with a simple name and password (no special characters). 2) Connect your phone to this new 2.4GHz network. 3) Now try the setup process in the Ecovacs app again with the robot and dock close to the router. This almost always works.
IF THAT DIDN'T WORK Some mesh network systems or routers with advanced security settings (like WPA3-only) can block it. Try temporarily enabling WPA2/WPA3 mixed mode or just WPA2 on your 2.4GHz band during setup.
HEADS UP The robot needs a relatively strong 2.4GHz signal at its docking station for reliable communication. If your dock is in a far corner of the house, consider moving it closer to the router for the initial setup, then you can move it back.