DirecTV app constantly buffers

I have a Directv Gemini receiver. When we try to watch anything on the britbox app, it buffers every 30 seconds or so and is completely unwatchable. I have determined the issue is with the Britbox app based on the following:

- Streaming on every other app (Netflix, Hulu, HBO, Prime, etc) on the receiver works perfectly fine.

- The Britbox apps on my phone and tablet using the same wifi connection work perfectly fine. As does using a web browser on my laptop.

- Watching via the Britbox website on a browser that is installed on the receiver works perfectly fine.

I have uninstalled the app, rebooted, and reinstalled the app. Does anyone know how to fix this?