Good to hear it still works for you. I think that modem did run off a broadcom chip. It's still old, though. So you may want to think about upgrading. If you're in the US and are on Comcast, here's a few options for you. Having a modem that supports more than the 4x4 channels the 6121 will give you a more stable, consistent connection so you'll get your 100 no problem.
Netgear Cm600 if you want to go under 100, I think you'll be able to get 500+ from it. I think the limit is around 700, but 500 is much more attainable.
https://www.amazon.com/dp/B06XGZBCKP/?tag=snbforums-20
Netgear CM1100, if you want to go all out, be done with it and sit on it for 5 years:
https://www.amazon.com/dp/B07Q5VM51Y/?tag=snbforums-20 I use a earlier model of this modem, the 1000 and get 950/42 off it.
The ones I listed here are all broadcom chips and you'll be leaving the crap the Puma 6 chip gave you behind.
I hope that helps you in the future.