I had the hardest time trying to connect my Deco M9 pucks in a daisy chain. My network is linear so I would expect the main puck to connect the the second and then the second would connect to the third;  Main -> #2 -> #3. For whatever reason, #2 AND #3 would always connect to the main. #3 would not connect to #2 which is closer and #3's internet quality was poor. Sooooo after months of searching on the internet etc, I had an idea to try to fix this. I grabbed a pie tin and covered the main puck. Then I rebooted #3 and it connected to #2! Now my network is the way I would expect and have better speed at the furthest part of my house! Hopefully it will stay this way. My helpful hint to those who have the same problem. Don't forget to remove the pie tin  and make apple pie