@RetiredInFl 

#1 I have not seen a single M9+ for sale on line, not sure if TPLINK packages it that way. 

#2 It's my understanding that ethernet backhaul does not work when running the M9+ in access point mode at this time. With only one device, you have no need for the backhaul since it is only for Deco-Deco communications. 

#3. Yes they can be enabled/disabled independantly.

Just curious about why you need the Xfinity Gateway? I use a Netgear modem (CM600 with no routing) feeding my Deco system of 3 M9+ and one M5. 

@kevinsrq 

https://www.walmart.com/ip/TP-Link-AC2200-Smart-Home-Mesh-Wi-Fi-System-DECO-M9-PLUS-1-PACK/886702132

(weird, last night it was $99,  Put it in my cart while waiting for reply to my message at $99 and this morning it's up to $169 with cart changed as well).

https://www.bestbuy.com/site/tp-link-deco-ac2200-tri-band-mesh-wi-fi-5-router-with-built-in-smart-hub-white/6359111.p?skuId=6359111

https://www.microcenter.com/product/607977/tp-link-deco-m9-plus-ac2200-smart-home-mesh-wi-fi-system-(1-pack)

Also a couple on eBay.from people selling extras from a kit. They can be found.

I much prefer the operation and control of the Xfinity router.  I had 3 M5's at one time and had strange issues with them with devices connecting to the one across the house when the device was literally 2 feet from the M5.  If I rebooted it it would connect to the closer one then drop off an hour later. Foundf it annoying.

Maybe BACKHAUL was the wrong term.  I wanted it to be a wired access point.  Backhal worked on my M5's in AP mode although I did have an M5 network. .  As an single access point I wanted it to be wired.  It's nice and small and would physically fit in where I want it.

Oh, I have to use the Xfi gateway itself to get FREE unlimited data where I am.  It cost $15/month INCLUDING unlimted data or I am capped at 1TB/mo. .  I have 2 Nest outdoor security cams that use my total data allowance and more each month.in HQ mode.  I can buy unlimited data for $50/month with my own router or pay $10 per 50GIG overage.  The cheapest way was with the Xfi Gateway router.

@RetiredInFl 

1. Yes, but most functions would not work, similar to the M5.

2. The mesh and backhaul will still work so you can run the first M9 to a switch, then have that run to other Deco M9s and it all function.

3. Yes, you can but not both, one wireless band must be enabled. You can also enable the guest network and disable either band as well.