Connecting Gemini to a receiver

We currently have Dish, which comes in through our receiver. However, when we plug in Gemini to that same location, we only get audio. Does anyone know why this is happening? Gemini works fine plugged into the tv's HDMI but as expected the audio is only going through the tv, not our surround sound.

If installing the Gemini into the receiver SAT IN is not supported, would we need to use the ARC out on the TV to the receiver?

Thanks!