My immediate reaction was, it’s your streamer. Then I looked at your streamer. I had a Grimm in my system for a while. It sounded very good, definitely worth the money. Sonically it was not quite as good as mine… but it was much less expensive.
But thinking about your problem. I put a very high probability that it is that your streamer cannot cope with either your power or internet connection. Aurender streamers get very heavy as the go up in performance. The Grimm is very light weight… indicating to me it is lacking massive electrical and vibration isolation. That would account for it sounding good in my system and yours when power and the internet is quiet. The Aurrender has massive electrical isolation from outside and cashing to make up for bad internet performance. My streamer sounds exactly the same at all times. While there is a very slight increase in system performance late at night… it is the whole system related to the power grid.
I recommend borrowing a Aurender W20SE. I bet the problem goes away. I would think even an Aurender N20 will significantly if not completely mitigate the problem.