My deco remains on blinking blue .. I have a deco unit (m4R) which works fine and is connected through ethernet through ISP modem. Another deco device 'hallway' - (E4R) connects through wifi and works

I was using the main Deco e4 and decided to replace with M4R i.e connected with ethernet cable. I am trying to use the old Deco e4 as a satellite. I have two. One is connected successfully and the oth