Cable Modems: Information About High Speed Internet and Broadband Access The Cable Modem Information Network
 Cable Modem Home - Forums - Statistics - Sign Up - Search -
Cable-Modem.Net Forums / Troubleshooting / Directly connected to modem fast, but slow through router
Author Message

# Posted: 6 Apr 2008 21:10

I have a 3 MB cable internet connection through Atlantic Broadband. I have Motorola Surfboard 4101 modem. If I connect my laptop directly and do a speed test through I get results in the high 2's (around 2.8 MB). As soon as I put any type of router in, I'm usually at or below 1 MB from the same test site. I've tried EVERYTHING and can't figure it out. Anyone have any ideas? It just seems to have slowed down in the last week or 2. I have a Cisco 501 PIX connected to the cable modem. I've also tried a Linksys WRT54G and got the same slow results with both. I set my outside interface on my PIX to 100Full instead of having it just set to Auto and that didn't help. I'm currently not getting any CRC or frame errors on the outside interface on the PIX that is connected to the cable modem. Thanks!


# Posted: 7 Apr 2008 21:56

I've tried wired and wireless. No difference.

Here's my modem stats, but like I said....single computer connected works fine.

Downstream Value
Frequency 681000000 Hz Locked
Signal to Noise Ratio 27 dB
Power Level -3 dBmV

Upstream Value
Channel ID 4
Frequency 31009585 Hz Ranged

Power Level 43 dBmV

# Posted: 7 Apr 2008 21:59

And I also updated my Linksys WRT54G to make sure I had the current firmware. Nothing has changed on my end except the speed slowed down!

# Posted: 8 Apr 2008 09:29

I know there's gonna be some reduction in speed because the connection is shared by multiple computers. And I've tried it with just 1 device hooked up to the PIX or to the Linksys and I'm still at a meg or below.

I know the ISP assigns the IP to the 1st device past the modem. And every time I switch devices I have to power cycle my cable modem so the modem pairs it's self up with the new device. And I get the same IP address from the ISP.

Like I said, nothing had changed in my configuration in years and it just slowed down out of nowhere. That's when I started trying different devices to see where the problem is.

# Posted: 9 Apr 2008 07:55

Well...I tried a Cisco 1760 Router too and got the same results. Speed drops below a meg. But what I tried that DIDN'T slow things down was hook up an XP computer with 2 NICs to the cable modem and do internet connection sharing. Never dropped below 2 MB from the remote computer and ran at 2.5 MB or higher from the computer directly connected!

Any ideas? I've run out of them other than getting a new cable modem.

# Posted: 9 Apr 2008 16:58

It was the cable modem. Talked the cable company today into swapping out my old Surfboard 4100 series for a newer Surfboard 5100 series. Hooked it back up to the Cisco PIX and everything is running like a champ again!


# Posted: 14 Apr 2008 22:56

i have a queston, i have magic jack (similiar to vonage) cheaper, you have to leave your pc on as it connects to a usb port on pc. is there any way to connect to the router/or cable modem and not the pc. there is a looks like some kind of plug on back of router and a cable is avail that has the correct
end on it with a usb end on the other. is this also an output from the cable
modem since it is power up all the time would it work...


# Posted: 14 Apr 2008 22:57

make that back of the cable moded


# Posted: 15 Apr 2008 07:57

Thank you, the magic jack works just like vonage, however you plug it into a usb port, and the pc has to be on to power it up plus to receive the ip address for it, what i was trying to get around was not having to leave the pc on all the time, was thinking there should be a way to plug into the router since it is on all the time..its not a big thing but just wondering and i appreciate your answer...jim


# Posted: 30 Apr 2008 12:34


The Magic Jack cannot be plugged directly into the cable modem. The software to run the Magic Jack hardware runs on the XP machine.



# Posted: 31 May 2008 10:21

Just thought I'd add a solution to the slow connection speed issue. I had slow connections and "site not available/found" types of problems as soon as I put in a Netgear router. Tried lots of things, but found what worked for me was locating the actual IP addresses of the DNS servers used by TWC (in my case) and entering those into the Primary/secondary spots in the Local Area Connection properties on each computer. Runs smooth as when directly connected now.

This topic is closed. You can't post a reply.
Free Motorola Surfboard Cable Modem Offer! FREE CABLE MODEM! When You Order Internet Service with Comcast, Cox or Charter

Cable Modem Home | Cable Service | Topics | Modem Information | Broadband Sites | Download Guide | User Support | Contact Us
All content published by, Chicago, IL, USA.
© Copyright 2009 All Rights Reserved

Powered by forum software miniBB™ © 2001-2006