Can DirecTV *STREAM* be used with Xfinity instead of AT&T internet?

Yes, it is perfectly compatible with any ISP, including Xfinity Internet. Think of it like this. As long as your mobile device or computer can connect to the internet ‘reliably’ and with quick speeds, directv stream should work PERFECTLY FINE. If you weren’t already aware, there is always better reliability with a wired Ethernet connection however wireless Wi-Fi does work too. Once you get Xfinity Internet installed, you’ll need to update the Wi-Fi settings for your streaming device. This will involve connecting to the new ssid (wifi network)/router.

HOWEVER, there is one pre-requisite. You MUST have a static IP address in order for DIRECTV STREAM to properly identify your home network, ensure you are getting the 20 simultaneous streams, as well as keep your local channels and RSNs accurate. Otherwise, you’ll face many issues with having to change your location over and over again until you get stuck since there are only 4 location changes per year. 

Make sure have how much data Xfinity will allow for the plan you choose as well. I am pretty sure they have data caps.

That isn't true.  What you need is an address that very very rarely changes.  Some ISPs provide that with a dynamic address - mine hasn't changed in at least 3 years, likely much longer.  Unfortunately, others don't - hence the problems some people have with DTV Stream loosing track of the "home" network.  (Other services use different approaches to determine the home network, but those have their own - if different - problems.)  Requiring users to get true static addresses isn't really a good solution - some ISPs don't offer them at all, while those that do charge a (sometimes quite large) premium and (depending on how the ISP implements them) they can have security and privacy concerns.  However, for users whose ISPs have actually changing dynamic IP addresses, there is no other good solution with DTV Stream's current approach, and it isn't clear that an end user can always know if they'll have a problem.

So telling a user they MUST have a static address is silly, but warning them about the problem is reasonable.  The real issue is that DTV Stream's approach is bad, but all the alternatives raise problems for either DTV or for the users, and I'll assume DTV doesn't want to raise problems for themselves, so the users "suffer".

I used to have Xfinity and the dynamic IP they give you rarely changes. Maybe once every 8-12 months. But remember their data caps. If you are on a plan with a data cap you want to make sure you have enough to stream Directv Stream. 

I'm new to Direct Stream - just started yesterday.  We are trying to evaluate Direct Stream.  We've been an Xfinity cable TV customer for many years but it's just gotten too expensive.

We have Xfinity cable modem service and I know the IP address is NOT static.

Tell me more about "home" network.  What does that mean?  And how does that impact our service?

Bill

As described earlier, that isn’t the issue - they determine your home location for the purpose of deciding locals and RSNs differently (generally by using your billing address for devices without GPS).

The issue is that DTV gives your home network special consideration. Specifically, you can have up to 20 devices connected to your home network streaming the DTV service simultaneously, provided you have the internet bandwidth to support that (so effectively unlimited TVs, mobile devices, and computers - at least I hope no one needs more than that). But it only allows 3 simultaneous devices that aren’t on your home network (and only 2 can be TV streamers - the remaining 1 has to be a mobile device, though all can be mobile devices). When your IP address changes, they now think all the home devices are away from the home network, so have the 3 device limit applied. You can reset what address is considered your home network, but only 4 times a year. 

So if your ISP almost never changes your address (and some ISPs are like that - my “dynamic” address hasn’t changed in at least 3 years), then you are good. If it does change it often (and some change it frequently) then it would be a problem.   Do you know for your specific case how “semi-static” your address is?

Both DTV and some of the customers who offer info here recommend a static address for customers who have often changing addresses - some say you need to have a static address to use the service at all regardless of whether this is a problem for you or not, which is silly. I think DTV made a major mistake by using the address that way, since a significant part of their customer base could be impacted by this. Forcing a customer to have a static address is quite problematic - not all ISPs offer them, those that do always charge extra (sometimes a lot), and configuring to use them is sometimes less automatic than a dynamic address, which can be an issue for less technical customers. Unfortunately, there isn’t a really good alternative if they want to designate a home network for this purpose. A couple of their competitors define a home network using different criteria, and those also have problems, just different ones.