Slow/dropping internet conection?

It's me again. I was able to get into my Win 10 computer, but hit another snag.

The internet connection is slow as molasses in January, and the computer keeps dropping it. We have a new modem/router from Comcast, and this doesn't happen on the other desktop, the laptop, the tablet, or the phone. First it wouldn't connect at all, then it kept dropping the connection, like the thing has a mind of its own.

So I'm wondering if it's Edge (I tried downloading Chrome, but didn't get anywhere with that), or the comm card, or Win 10 itself. I tried looking online, but obviously wasn't asking the right question or using the right terminology.

Any thoughts?