It sure can be a problem,,,,,,I had an antique cable modem that I had for years, and every time I bumped the desk, it would stop working. I would have to re-start the thing. So I called Comcast and the man said that this was a problem with that particular model. And it also was slow. I went down to the office and they gave me a new one(you have to take the old one back with its paperwork), and this new one flies!
My grandcat even tipped it over one day and it kept right on working.
Jane
I almost forgot,,,,,Also if the technician ever comes to your house, like they did when they initially hooked us up, they will do a test on the cable line itself from the pole. If that cable is really old, it can slow things down a lot.