Can't Stream / Watch on 3 TVs (2 Direct Genie Boxes and 1 Firestick)

That can happen if you're not at your home network location, or if your internet provider changes your IP address too often. 

This is a problem with the mechanism that DTV uses to determine your "home" network, which is the local network that allows effectively unlimited simultaneous streams of the DTV service.  They use the address of the network that you first logged into the service from, and implicitly assume it will never change.  That works fine for some network technologies and ISPs (AT&T seems to never change the address - I've had the same one for at least 4 years, across restarts and even router change-outs).  Others, like fixed wireless (cellular hot spots) seem to change all the time.  And yet others are somewhere in between.  This means the service is problematic for some users, depending on their ISP.  If your IP address changes only occasionally, they do allow you to change your "home" address up to 4 times per year without having to get Support involved.  Their info on this is here.  (I've never had to do this personally, so I won't swear it works.)  If your address changes somewhat more often, you can contact Support, and they (usually, I'm told) will reset the counter if you explain the situation.  OTOH, if your address changes all the time and you need more than the 2 devices, you would likely be better off with a different service.  (They all use some rule to figure out the home network, but I think only DTV uses this particular rule.)