Customer Ratings & Reviews

I'm returning to the store first thing tomorrow. I spent an hour off & on the phone with my ISP trying to get the thing activated and tried a direct connection to my cable wall outlet. Nothing worked. The ISP tech support guy agreed that it is definitely a problem with the modem. Oddly, this was one of the modem upgrades listed on my ISP's compatible hardware list. I ended up having the ISP re-activate my older, slower Surfboard modem for now, just so at I'm still able to access the Internet. I'll probably spend a little more for higher speeds and I may even stick with the same manufacturer to give them one more chance... but if they fail me again, I'll be changing to a completely different brand.

This thing is slower then my motorila sb5101 and it shows it is running in gig it still hangs and slow on dowload which came out around 23 down and my old motorola was running 26 down. Will be returing this along with the cisco ea3500 router.

I bought it to avoid paying the Comcast monthly rental fee. It worked great for 3 days then began to constantly reboot. I called Comcast and they said it was the modem. I exchanged the modem for an exact copy and the same thing happened. Called Comcast and they sent a technician over. I checked the power levels and even with attenuating the line signal, the technician couldn't get it to work. It would just constantly reboot itself in the following order: 1st light green 2nd light green 3rd light green 4th light green and 2nd light blue. after a few seconds... 4th light off and 2nd light green then reboot..... returned it to get my money back.

I bought the SB6121 because I just moved into an apartment and the only internet service in the building is DOCSIS. During the first month the modem was a little iffy, but worked well enough to look past and it played nice with my router. Unfortunately for me, on the 32nd day I owned it, the thing stopped receiving signal. I know it was the 32nd day because the day before I threw out the packaging and, regrettably, the receipt because a month had passed and everything was fine. $100 down the drain. I've replaced it with a Zoom 5341J and so far it's working better than the SB6121 ever did.

Thought I was getting a top of the line device but this device is just top priced. It has great difficulty connecting phones and laptops wireless. They drop and have to reconnect every ten minutes or so. Very often I cant even compose an email without having the modem loose connection and having to start over. Normally, I have to attempt to log in to the internet three or four times before I get in and then its laggy and slow. The PS3 and XBOX360 work great, just not the rest of the electronics in the house. Dont purchase this device.

If you have Comcast, don't waste your time with this piece of junk. I wasted hours and hours on calls with Motorola and Comcast only to learn from the Comcast tech they rolled to my house that many customers are have issues with dropped internet connections with the 6580. The Comcast tech said each morning that his management is reminding the techs of the many customers with 6580 issues and the solution is to purchase a non Motorola product. I recommend that Best Buy drop this product and purge their inventory ASAP!

While we did not have any problems with this modem, the maximum speed is not as fast as the Zoom DOCSIS 3.0 model. We exchanged for that model.

I wanted to upgrade my Cable modem to the newest model. So I plugged it in to set up and switch and there was a short in the modem and blew out my network card. Returned it. My second attempt would not connect with Comcast. It kept cycling and restarting and never full connecting. I went back to my old modem that works fine and returned this disgusted. I strongly urge to avoid. Try any other modem but this one.

This product lasted a total of 9 months before it needed to be replaced. I am the only person that uses this modem, 1 bedroom apartment, only person that lives here. I'm extremely disappointed in the quality of this product.

You would think that if they are going to sell a product at a store in your area that they would know what providers allow the use of this device.

I'm very disappointed with this modem. It lasted just long enough to fulfill the warranty and DIED. Not impressed!

I tried two of these modems and both of them didn't work. I went to another brand and that took care of the problem.

Returned product. It would not connect. Stayed with my current DOCSIS 2,0 modem.

Does not sync with Time Warner Cable. Do not buy will not work.