Hello everyone,
 

I could really use some help and guidance here. I'm a bit stuck and hoping someone can offer some advice.

I have 5 M5 units and 3 M9 units, though not all of them are currently in use.

My house has two floors and a rectangular layout, with a basement beneath the first floor. The main internet connection (1000 mb fiber) enters in the center of the first floor, where my main Deco (M5) is located and set up as the Wi-Fi router.

On the second floor, there are Ethernet outlets connected to the main Deco. However, I couldn't get Ethernet connections working on the first floor or in the basement, except in the room where the main Deco sits. Unfortunately, this room has poor Wi-Fi reception due to concrete walls, so I'm unable to link other Decos to it wirelessly.

Here’s how I’ve set up the satellites:

• An M5 connected via Ethernet backhaul on one side of the second floor — this setup works great, and the second floor has excellent Wi-Fi coverage.
• An M9 Plus, also with Ethernet backhaul, on the other side of the second floor — everything is perfect here too, with great Wi-Fi coverage.

Now, here’s where the issues start:

• The living room is on the first floor, directly below the second-floor M9 Plus.
• The basement is beneath the living room.

In the living room, I have another M9 Plus, which connects wirelessly to the M9 on the second floor. The speed is around 100 Mbps, but the signal strength is weak. In the basement, there's an M5 connected wirelessly to the living room M9. The speed there is only about 20-30 Mbps.

Here are my questions:

1. I also have one more M9. Should I use it as the main Deco (instead of the M5), even though no other Deco will be able to connect wirelessly to it? Would this setup bring any benefits?
2. Would placing the M9 in the basement improve the speed there? However, the basement TV, which uses Wi-Fi, is rarely used, so I'd feel like the M9 would be underutilized there.
3. Is there any way to improve the signal strength in the living room?

Thanks in advance for your help!