Streaming Audio Cuts Out Frequently

When I am listening to Amazon Music Unlimited I frequently get brief cut outs in the sound.

I have considered trying hi-res streaming.

For that to be meaningful I would have to spend some money since my current streaming set-up is Apple TV into a Schiit Modi 2 Uber via optical. I have not even begun to explore an economic upgrade of those components.
And unless I can get the cutting out issue sorted I’m not even going to consider upgrading my system. No sense in hi-res streaming through good gear just to have it cut out every 10 or 15 minutes for a second.

So this is a two part question: First, where should I start looking for the cutting out culprit? Is it the internet service? Is it the cable modem? Is it the router? This problem does not occur when streaming movies etc.

Or could it be the Apple TV?

Second, what would be an affordable (under $500?) gear route to taking advantage of hi-res streaming? As far as my modest sound quality needs, I’m generally satisfied with the little Schiit and I will not be streaming to anywhere else in the house so I don’t need to pay for that capability.

Thanks for any and all advice.
George