I used a really old Surf Board for a while when I got cable in my area, this was like 1998-2000 or so, had the modem for a few years, it died and they got us an upgrade to a DOCSIS 2.0 Surf Board, and I used that fucking thing for like 13-14 years.
It kind of blows my mind that a cable modem can last that long, I never even thought of upgrading it because I'd had it for so long and never had any issues with it. One night though it started to have issues syncing up with my cable provider, something about the frequency ranges they were working with weren't playing nice, too much noise or something.
Replaced it with a DOCSIS 3.0 Surf Board and my speed went from max speed of 3.5-4.5MB/sec when the speed would occassionally jump up to just averaging that speed and then bumping up into the 7-8MB/sec range when it felt like it.