@Xequtor 

How are satellite Deco D and E connected to the main Deco?  Via PLC as well as wifi?
 

To have a good PLC signal, it is recommended to plug the P9 Deco directly into wall plugs.  Can you test without going via the UPS? 

Is it possible to install a Deco in the hallway?

How are the walls between the rooms and between the rooms and the hallway?

  @yves_b 

Deco D and E are connected over Wifi only to the main Deco. Deco E is directly plugged to the wall plug. I guess I can plug D to the wall plug as well, but the main Deco cannot be plugged to the wall, it has to be plugged to the UPS in order to assure that it won't go away suddenly while I am in a meeting, if the power is cut. One day, when looking at the Deco App, I saw that the Deco D was connected to Deco E, not the main Deco the PLC and Wifi for a brief moment, even though Deco D was connected to the UPS. But after some time, Deco D connected back to the Main Deco over Wifi. 

 

yves_b wrote

Is it possible to install a Deco in the hallway?

 

Do you mean a new Deco or moving an existing one? I can add a new Deco in the hallway as well as in any other room, except F and G. But is it guaranteed that the other Decos will connect to the new Deco, rather than the main one? I was hoping that Signal Preference will be available on my Decos so I can force such connections. Won't hesitate to buy new Decos if that would solve my problem. 
If you suggest to move an existing one - only Deco I can move is Deco E

yves_b wrote

 

How are the walls between the rooms and between the rooms and the hallway?

Do you mean how tick or what material are they made of?

  @Xequtor 

If you insist of having Main Deco connected to UPS, Deco P9 model is not for you. Powerline link can't be reliably established through UPS, which means this very useful feature of P9 will not work. P9 firmware does not support Connection Preference feature which allows to daisy chain Deco nodes, and maybe never will. 

Because of that, I would recommend you return P9s.

Instead, I would recommend Deco M9 Plus. These support Connection Preference feature and also better suited for daisy chaining.

Deco M9 Plus are not sold in single units, only in 2-unit and 3-unit sets. With careful planning and testing, 3 units may be enough, but if you want good WiFi signal in Room D for sure, you will need four. Which means, you should buy two 2-unit Deco M9 Plus sets, making it total 4 units.

The placement of Deco M9 Plus will be the following:

Room B - Main Deco

Room C - Satellite Deco

Room D - Satellite Deco configured to connect to Room C Deco

Room E - Satellite Deco

  @Xequtor 

I am wondering what are the obstacles to the wifi signal.  That should guide where to position the Deco.

If the walls between the rooms are the main obstacles, moving Deco E from room E to the hallway might help.

If the main obstacle is between room C and room D, then there is no benefit in adding a Deco in room C.  That would also explain why Deco in room D does not connect to the Deco in room C and connects directly to the Deco in room B.

I would also test plugging Deco D into the wall, and check if it establishes PLC connection with Deco E, varying the location of Deco E.  It may take some time for the Deco to adjust the topology of the mesh.

  @Alexandre. 

What if I move the Deco in Room D to Room C? And then add a range extender AX1500 (Already have one) in Room D and use its ethernet port to connect to my device in Room D. Would that solve it? 

Unfortunatelly I can't return my Decos

  @yves_b 

Actually the hallway has another wall with a door, which splits it into two. So it will be the same situation. Also there aren't any differences in the walls between the rooms, they are all the same concrete and wood mixture walls. 

Xequtor wrote

  @Alexandre. 

 

What if I move the Deco in Room D to Room C? And then add a range extender AX1500 (Already have one) in Room D and use its ethernet port to connect to my device in Room D. Would that solve it? 

 

  @Xequtor 

You can try that, but there is no guarantee Range Extender will connect to Satellite Deco in Room C. It is possible it'll connect to Main Deco. Still, worth trying.

You have almost impossible to solve situation with Deco P9s you have. I would recommend, just like  @yves_b suggested, to plug Main Deco directly to the electric outlet and see if it can establish powerline (PLC) connection with Satellite Deco in Room D. You can do that for testing purposes at least.

  @Alexandre.  @yves_b

Today I connected the Deco in room D to the wall plug. After an hour or something, the connections changed (or at least I see difference in the Deco App). See the image:

Office is my Main Deco, Bedroom is Room E and Xequtor's is Room D (The problematic one). Both satelites Decos were connected to the Main Deco over PLC and Wifi. Xequtor's Deco still shows Weak signal but it seems to be faster than before. I don't know what happened and if this situation will be maintained even in case the electricity is cut then restored back. I would really prefer to keep my Room D deco connected to the UPS since I need it connected to internet even in a case of power outage, but I guess fior now I will keep it like this.

Today I was also thinking to lay an Ethernet cable between Main Deco and the Deco in Room D if nothing else helps.