TheoTM wrote

I still have the old fashioned wifi setup in my house, with on the ground floor the modem with an external wired wifi access point and on the second floor a second wired access point. Both access points are of different brands and have separate SSIDs.With this setup I have fairly good wifi coverage inside the house (although manual switching is required) when going upstairs or downstairs, but a rather poor coverage in my backgarden.

 

What I would like to have is seamless roaming inside the house and in the garden. My idea is that the best solution is always to have a wired access point if possible. So, to my opinion, the following will be the best configuration for optimum wifi coverage using three Deco M9's:

1. A wired M9 on the ground floor. The location is on the front side of the house.

2. A wired M9 on the second floor. The location is more or less in the middle of the house.

3. A wireless M9 on the ground floor, located at the back side of the house to give optimum coverage of the garden.

With this placement I assume that all three access points see each other.

 

So, here are my questions:

1. Does the mesh functionality (backhaul) still work, because I will have two wired M9's and one wireless M9?

2. Do I still have the optimum wifi coverage on all locations, or is it better to only have one wired M9 to the modem and the other two M9's wireless?

 

I'm really looking forward to any response!

 

@TheoTM - Hey there! I'm a Deco M9 user - not support, but from what I understand:

1) Yes the mesh will still work - your second floor M9 Deco should show an ethernet backhaul to the main ground floor Deco. The "back side" Deco should show a wireless backhaul to the main ground floor Deco (assuming it's closer than the second floor Deco). (Note: Make sure you upgrade to the latest firmware (check whether you have v1 or v2 Decos) to see the backhaul.

2) It's always better to use wired when it's available to you.

@TheoTM 

Adding to what @crizthebard said.

I am also M9 user, own pair of them, one is wired another is wireless. 

Not wired M9 really shines when it has good 5GHz signal for its backhaul to another (wired in your case) M9. 

I suggest you run test for 5GHz signal quality, before you buy M9. You might find as a result of these tests that you either need to move wired M9s around, or buy 4 M9 instead of 3. Note that it is hard to find single M9, it appears they are sold in 2-packs and 3-packs only, which means before you buy you must decide if two 2-packs is right for you or 3-pack is enough as you planned.

I am assuming locations #1 and #2 for your wired M9 is where your wifi access points currently are. I am also assuming they provide 5GHz signal, not just 2.4GHz. 

So, for the test:

1. Install WiFi analyzer on your smartphone to see signal levels. I recommend WiFiman from Ubiquiti, but there are other similar apps.

2. Go to location #3, where you plan to place your wireless M9.

3. Turn off and on WiFi on your smartphone to get clean readings.

4. Run WiFi analyzer and see what quality of 5GHz signal you are getting from either your AP at location #1 or AP at location #2. It is critical that you check 5GHz signal quality, not 2.4GHz.

If you can get Good/Great (WiFiman terminology) 5GHz signal at location #3 from either one of two locations, your wireless M9 will do just fine and 3-pack should work for you.

I would also suggest doing it on sunny day, if possible. You'll be surprised how much solar radiation impacts 5GHz WiFi.

Finally, I am assuming you need M9s to just improve WiFi signal, which means they will be running in AP mode. After you configured first Deco M9, which will become Main Deco, get into smartphone Deco app configuration setting, under Advanced change Operating Mode from default which is Router, to Access Point. After that, proceed with configuring other M9 and adding them to your mesh, according to manual.

Thanks for your replies, it makes things more clear!

In the meantime, I kept on googling and found a good description on the backhaul on the website of TP-Link itself. Among others, is states that combining two wired and one wireless M9 is no problem, thereby preserving the mesh feature by using both Ethernet and wifi backhaul.

This is the link to the faq:

General questions about Ethernet Backhaul feature on your Deco | TP-Link Nederland (tp-link.com)