@Sunshine still connected to the wifi with no network, and its across the whole network, main and extended and the one thats connected via ethernet.

The lights dont change at all, all "green"

a quick update on the topology - (1) main router getting fiber WAN connection with DHCP on. (2) is the RE450 connected via 2.4GH mode and is getting great reception and by itself works awesome. (3) is the backup router connected 20 meters away with Cat6E to the (2) Re450. ONLY when the Ethernet is connected, the WAS connection on (1) is dropping every minute or so for a period of 5-30 seconds. (3) is connected to LAN1 and not via WAN - doesn't see it or gets connection for some reason. management system is inaccessible in this mode thus no DHCP on the router ( i guess since i have no way of checking). i switched the (3) router to a different one, same story, i switch the cable to a short one in close range - same story. no firewall rules on (1) router. ideas? for now it seems that the RE450 is the problem