I recently installed two wireless cable boxes and learned that the Netgear Nighthawk I owned would not support two wireless cable boxes (it kept crashing), so Xfinity suggested that I rent their CGM4140COM that is an all inclusive router/modem/phone port. For the most part, this has worked fine (I've had to reboot the boxes a few times), but I would prefer to buy than rent. Is there an alternative to the CGM4140COM that I can buy?
Note: The Wireless TV Box will not work with customer-owned modems ...
I myself recently got an Xi6 wireless box after upgrading to the X1 xFi Gateway and I've been pretty happy with the service so far.
However, if you prefer to own your own internet equipment, I suggest getting a couple of Roku boxes and install the Xfinity Stream App on each one, as they will work in lieu of the wireless Xi5 or Xi6 cable boxes, although you do lose some minor functionality.
See this Knowledge Base article for more details.
That said, your choice of modem or gateway will depend on what services you have. Please check out https://mydeviceinfo.xfinity.com for a list of compatible devices.