Cannot add new XE75 Pro deco unit to my existing deco network (also XE75 pro)
I have an existing two-node Deco XE75 pro Wifi mesh network. Connection is:
ISP Router --Ethernet -- Main Deco (XE75 pro) unit --Ethernet--Satellite Deco (XE75 pro) unit.
It has worked well but one bedroom has weak signal, so I'm trying adding another XE75 pro, and got stuck here that the deco app couldn't find this new deco unit.
I have tried following connection options
1) ISP Router --Ethernet -- Main Deco (XE75 pro) unit -- WiFi - Satelite Deco
2) ISP Router --Ethernet -- Main Deco (XE75 pro) unit -- Network Switch - Satelite Deco
so far none option worked. always stuck at "cannot find new deco unit" on app.
I have tried different deco unit (I bought additional 2) and different network cable, still no luck.
What could go wrong?
Thanks.