I've been doing a bunch of Comcast Business Class internet setups lately. With 25mbps download speeds and a affordable pricing for Small to Medium Enterprises (SME's), who can blame the customers. I'd do it too.
The issue with the cable connection is that it isn't guaranteed. This means it could go down for any reason what-so-ever and there's really no re-course. Not good for an office fully of paid salaries trying to accomplish daily tasks. So I also have a backup T1 connection. Funny because historically T1 connections were soooo much faster than speeds at home.
I usually install my own equipment (ROUTER) behind the MODEM. When doing this, 2 items I notice.
First, DHCP is turned on the modem. I don't want that because I have a static IP. So getting into the SMC modem is as follows:
-open INTERNET EXPLORER (big blue 'e' on computer).
-at the top where you type in a web site, erase everything up there.
-hit ENTER (or RETURN) on the keyboard.
Turning off DHCP should be pretty obvious.
Secondly, I couldn't get through my router with a public IP from a remote location so that I can access the equipment behind it. There's an firewall setting that has to be changed in the SMC modem to make it work. Simply:
-checkmark "Disable Firewall for True Static IP Subnet Only."
That's it. Enjoy your highspeed, really, really fast business class internet from Comcast with a static IP.