When you rent a wireless gateway* from Comcast (as most customers do), by default Comcast enables another wireless network called xfinitywifi for use by other Comcast and Cable WiFi Alliance customers. This is a really bad idea:
- Security and privacy are put at risk by opening up service to outsiders in shared equipment. (Claims that outsiders are completely walled off are disingenuous -- there is always a risk.)
- Internet service is degraded by the additional traffic. The carrier wireless gateway is a cheap low-end device with limited processing capacity (and is a common cause of connectivity problems in general).
- Wireless networking is degraded by the additional wireless traffic. Wireless bands are already crowded and limited in many areas, and this just makes things worse.
- It's not good for guest Internet access (as claimed by Comcast) because it won't work if your guests are not Comcast or Cable WiFi Alliance customers. Set up a private guest network on your own wireless router for your guests.
- Comcast is running its business for free out of your home on equipment you are paying to rent.
The better solution is to never ever rent a carrier wireless gateway. Instead, buy your own:
- DOCSIS cable modem (from the approved list, like the excellent Motorola SB6141)
- Wireless router (See Choosing a Wireless Router)
To be ethical and above board, Comcast should at least provide a free wireless gateway in return for supporting Xfinity WiFi.
- Comcast XFINITY WiFi: Just say no
- To Xfinity WiFi we're all hotspots, but you don't have to be
- Are You Sharing Your Wifi?