@PaulPP See this: Deco Mesh Frequently Asked Questions. Yes, you can add one or few more units to your M4 3-pack. Also, they don't all have to be M4, if you could get better deal on M5 you can get it...

@Sprite I bought mine on Amazon, and this is sticker on the box: If you will be getting it from retail store, you could check the sticker before paying, and if you order it from online retailer you...

@Sprite I have two M9 Plus V2, one is Main wired to router, another is Satellite using WiFi backhaul. I bought them 4 months ago on Amazon. On initial setup they were upgraded, though the app, to...

@Izzy_R I am afraid I may have more bad news for you: it is possible Deco mesh continues broadcasting on WiFi 5GHz backhaul channel, even if Deco units all use Ethernet backhaul. You should test that...

I am assuming this is only the problem when Deco mesh runs in Router mode. For Deco in Access Point mode it would not be an issue.

@Izzy_R Have conversation with your housemate to find what is she actually concerned about: 5G or 5GHz? Cellular networks offer 5G for cell phones, where "G" stays for "Generation." 5G just means it...