@Kevin_Z Yes, I have both the M5 and M9+

The M5 was used on the roof top terrace (technically 4th floor but open air and housed in water proof box) and while the M9+ was used on the first floor.  The AP cannot 'see' each other between the floors and was connected via ethernet. I got 2 M9+ on the first floor, one indoor and the other one in the car poach with a glass door in between.  For the test, I took the m5 from the roof and place it in the car poach for testing.  All the APs were on ethernet connection.

I have read many other support document but the app interface shared was different from what I see.  I read somewhere that you can selective disable mash for client but was not available on my app.  I also cannot see which client was connected to which AP if I use any of the m9+ node as the main node.  When I set the m5 as the main node, I could see the client connected to the m5 (but not the switch to enable/disable mash for that client as mentioned on other support doc) but cannot see the client list for the m9+.   Basically, most of the support document is not helping as I could not see those settings and information for the m9+ node.

@Kevin_Z 

This is the screen on the M5 used in the car poach, cannot see how the node was connected to the internet and no options for the clients

Below is the app screen for the m9+, totally no info

@FoongWai Hey there, sorry, I'm just another user and can't really help, but is the 2.4ghz network fine on your Deco M5? I wonder if it's worth purchasing one