That's not affecting the cable modem. That's affecting how Windows accepts its internet connection.
http://www.speedguide.net/ is a good site that'll take a look at your Windows settings and configure them for your connection, make it a .reg file, and basically handle it automatically.
I work in the Cable Modem industry, and tell my customers to use this.
<P ID="signature">It doesn't matter if you’re 7'8" and weigh 100 lbs, or you're 4'9" and weigh 300 lbs, or black, green, or blue. That's Gene's greatest legacy to all of us - inclusion for the world. - Robert Blackman</P>