App won't work on my TV's

What do you mean it does not work? Any errors or messages? Are you a previous satellite subscriber? Using the same credentials for the service? If so, you need to use different credentials for each service. A known issue.

I hate those Smart TV apps. They never seem to work with the service. Do you have another external device to test? It's always best to use external devices.

 I have multiple Fire Sticks. No problem for years. Just to clarify, are you a DirecTV Stream subscriber or a DirecTV via Internet subscriber. They are different subscriptions. They both shared the same app.

Any internet. Install what? So you are still on Comcast internet?

So you are paying fees and have a contract? DirecTV via Internet has fees and a contract. DirecTV Stream has no fees or contract.

Thanks. Then you are a DirecTV subscriber and not a DirecTV Stream subscriber. They both share the same app but depending on your subscriptions determine the content. So the next question is are your credentials the same for your AT&T internet account and your streaming account? If so, I recommend that you go to your account for DirecTV and change the credentials for that service. The issues that you have described are as I mentioned previously with using the same credentials. All this took place when they combined are the services into one and supported Roku and Fire Sticks with DirecTV.

So glad your issue was resolved.