@Borjabmw 

My guess would be that the e3 in your room is 'too close' to another deco node, therefore when you enter your room the signal advantage isnt enough to trigger a move to the E3

Remember that in a MESH setup, when you move to the E3 you have added another HOP, to get to the internet.  This will double the latency and half the rate of transfer as data now needs to jump twice via this node.  

Therefore if your phone is connected to the M5 for example and getting 60% signal, when you enter your room there is no advantage to the system to move you to the E3 where you will get just 50% performance max..

Just my thinking!