Cable modem won't work with old router

Question

Cable modem won't work with old router

I think this may be related to recent posts about new cable modems installed and no longer recognizing Airport extreme or other routers.

In my case, I don't have an airport base station, but I am experiencing a similar issue.

6 months ago I had my home LAN and Netgear router all hooked into Time Warner Cable's modem. It was an RCA at the time. To save dollars, I switched to AT&T DSL. Ugh! What a mistake. DSL ***** big time.

TW Cable came out with an offer at I could go to high speed cable internet for less dollars so I switched back.

They brought out a new modem: Scientific Atlanta DCP2100R2.

My home LAN config hadn't changed. The router worked fine with the AT&T modem.

But when TW cable installed their new modem strangeness started.

I am running on my LAN both PC and Mac desktops, and a MacBook Pro laptop.

Once the new modem went in I can only run one machine at a time and have to recycle the modem if I switch. Regardless if it goes through the router or not.

Tivo is the same. If any other machine is hooked in, the modem will only recognize one machine. So Tivo network service can be the only thing connected, or my macbook pro, or the desktop PC. Only one "thing" at a time.

Complained to TW. They send out a tech who said he has run into the problem and swears it is because the new Scientific Atlanta DCP2100R2 modem does not talk with older routers. My routers are all at least 3 years old.

The only solution TW has is to pay outrageous sums for their own router. Hmmmm.

Has anyone else encountered this issue?

Is the Scientific Atlanta DCP2100R2 modem designed or spec'd out to only talk to one machine at a time, no matter if it is Mac or PC and the router doesn't matter?

Is Scientific Atlanta's DCP2100R2 modem only able to talk to a new "standard" with any router's?

Does anyone have any suggestions?

Thanks!

MacBook Pro, Mac OS X (10.6.2)

Posted on Feb 17, 2010 12:47 PM

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Answer 1

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Tesserax

Level 10

148,447 points

Feb 17, 2010 1:12 PM in response to Erik Fulkerson

Hello LisaToMac. Welcome to the Apple Discussions!

Although it is always possible that there may be a compatibility issues between this modem and a particular router, most likely, it may be the way Time Warner provides their service at your location.

For example, some ISPs require that you "register" the MAC Address of the network device that will be connected to their modem ... that could be a single computer or a router. Typically to get "around" this, we use routers that employ NAT so that the MAC addresses of these computers are not "seen" by the modem ... only the router's ... but, unfortunately, this doesn't work in all cases ... maybe like yours.

If, after performing a complete power recycle of your equipment, the modem still does not provide access to more than a single device, I would suggest that you demand a replacement modem that will.

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