Has anyone else had daily internet disconnections without cause?

For the last four months, our internet has randomly been dropping. It was initially only once or twice a week, but then it became more frequent. An Xfinity tech came out last month, because it was interfering with my job. The xfinity tech said that we needed a different router. So I spent the money and got a great router.

Within a week it dropped again. Now, it happens MULTIPLE times a day, probably more. I work on my computer and am constantly having to stop and wait and restart everything. I've lost at least a few hours of work this week alone.

Clearly it wasn't the router - but I've already spent the money and installed it.

I don't understand why the internet is suddenly up and down, when we haven't changed the service or hardware at all.

Does anyone have any ideas what could be causing it? If it happens much more, I will have to bite the bullet and sign up with another ISP. I cannot pay for the internet if I cannot work - and there is zero reason to deal with this much stress over something so simple as an internet connection.