I'm a "business starter pkg" customer replacing old equip.......

Hello boxdin and welcome,

Go to http://mydeviceinfo.comcast.net, then drag the business tier blue ball to your internet speed, look at the list of supported modems that you can use. Typically, the Comcast Gateways (CG) offered are SMCD3G, NetGear 3000, DPC39XXB. The fastest CG is the DPC3939B or DPC3941B with full 2.4G and 5G dual port WIFI. You can also use the Support feature on your Business Class Homepage, use Business Wireless Gateway in the search field and you can obtain information about the DPC39XXB CGs.

Hope this helps you out.

Thanks for the help, even that is over my head but I can figure it out. 

I could really use a schematic or diagram of how I'm supposed to wire all this up. Is there anywhere I can get such a diagram? Thanks Rick

You need to call Comcast tech support for any modem change.   They will need the model and MAC address of the new modem.  Otherwise what can happen is when the new modem is placed on the service it will pull the wrong boot file and setup wrong and you will have problems with it.   When you are on the phone with them you can ask them what to plug in where.

My quandary is; I thought I needed both modem and router. Evidently I only need a router, perhaps coz comcast supplies the modem (?). Is that true, if so I can return the comcast approved modem I got and now purchase a comcast approved router only???? That should be an easy install, its the whole modem/router combo that has me messed up.

Many Thanks Rick

boxdin,

Here is a schematic for separate modem and router

Comcast Coax----->[Cable Modem]<----->{WAN             LAN]<---Ethernet to local system(s)

                                                                     [    Router       WiFi]===WiFi to local system(s)

If you have lots of wired boxes, you might need an Ethernet Switch to connect all your boxes.

Honestly, I don't want to take lots of time managing network stuff - I want to spend more time on creative activities. So, here is what I use for CBI Starter:

* Cable Modem:  Arris(Motorola) retail SB6121 -- new SBnnnn or Cisco DPC3008 are fine if on Comcast list. DOCSIS 3.0 is a minimum requirement.

* Router and Wireless Access:  Apple Airport Extreme Basestation -- Easy configuration from Windows or Apple or, even, iPhone. Gigabit Ethernet and fast dual-band wireless work well. But, only three LAN ports. (see next)

* Netgear GS108 Gigabit Switch -- I use two because I have ten or so wired devices.

This is a perfectly adequate setup if you do not need fixed IP addresses. Good IPv6 support is there by default. Comcast can not share your cable connection with Xfinity WiFi. I have used this configuration for over 3 1/2 years have had no significant down time.

All my systems and communication gear are on UPS to isolate them from power line noise and glitches. This is as essential as a firewall for protecting your systems.

You do need to understand your end system's firewall capabilities, or lack thereof. Depending on your business needs this may require more help than I have supplied here.