Slow Cable Modems - Everyone Please Read

This is a really interesting discussion as I am based in the UK and have recently upgraded from 2Mb to 4Mb BB with my ISP, Blueyonder (Telewest). This all runs through a Telewest supplied Motorola Surfboard SB4100, which in turn is connected to an Apple Airport Express router.

But after ensuring all was restarted, etc., I saw no real difference in the speed...except our eMac!!? i.e.

After testing online I am getting approx 2700 kbps download and 350 kbps upload (just over 2MB on download).
We are running 3 Macs:
The two iMacs have 800Mhz processors with standard airport cards, that both show the same speed as mentioned above.
However, the third Mac, a lowly eMac...has a 1.25Ghz processor with an extreme airport card, and the download speed on that shows up as approx. 3.6MB.

I thought it might be the airport cards difference, but an Apple dealer has said that even the standard cards transmit at an 11 mbps.

So when I saw this discussion it looked like it could be the solution....but two problems:
1. Why is the eMac seemingly running at the higher speed?
2. My SB4100 isn't mentioned in the listings, so must be pretty old, but I cannot find the golden Motorola SB5120 in the UK?

Any clues and advice would be most welcomed.

In addition to the above, I've just received my Apple laptop back tonight (lent it to someone) and after testing that I'm getting an incredible 7.7mbps download (Even though I only have a 4Mb BB connection??).

There must be some hardware limitation or setting that is causing these low speeds on both iMacs.

Hello Broadcom,

Have you had a chance to check if the Next Level Communications gateway box (RG2000) includes a Broadcom chipset?

It is my last thing to check, before I switch ISPs (and, therefore, my modem)

Thanks in advance for your help,

This same logic has also been picked up by Blueyondr help, as I have received the following advice from them when I suggested that it was the Broadcom chip set cable modem problem.

"I refer to your comments regarding your broadband connection and MAC set
up. You have stated in your comments that you are able to receive the
correct download speeds on one of your MAC's however the other 2 are
affected. This points to a configuration issue and as previously advised
networks are unsupported by blueyonder. Try connecting one MAC direct to
the modem using your ethernet cable and see what speeds you get."

I've yet to try the direct connection as others are also connected, so need to wait until it doesn't disrupt, but I cannot disagree with his logic!

Check you DNS settings.

I've just checked the DNS settings. Although I had two DNS addresses, it is actually set to use DHCP (I think the old settings were just left in place from way back).

So I removed them anyway, and restarted the iMac (guess I wouldn't have to restart the modem?), but it's still showing the slower speeds.

Thanks for the suggestion anyway.

I'm seeing a big difference in download speeds with the Time Warner supplied Motorola SB5101. I thought it might be my wireless connection or the Netgear WGR614 router. I disconnected the router and plugged my iBook directly into the SB5101 via the ethernet. I use Speakeasy.net and ran the test. Consistent 1.5 - 1.8mbps. The I hooked up my old Dell 1ghz PIII and I get 6mbps. I had my Dell laptop from work and got 6mbps. I beleive what is being said. The connection speeds started OK but then have tailed off. I'm ready to try another cable modem. I'll see if TW has 5120s. If not I may try a DLink or Moto 5120 from Best Buy. I can return it. My last resort is DSL but then the problem may exist on DSL Modems. What about Speedstream 5100 DSL modem?

Kelvin

you need to contact your cable company and find the specific DNS settings for the cable company then put them on your settings. It worked great for me.

UK with Blueyonder/Telewest ISP

All my Macs are set to DHCP, i.e. no specific DNS settings. But I still have a problem with 2 x 800MHz iMacs running just above 2MB on a 4MB BB connection.

BUT...I have a lowly 1GHz G4 eMac and a 1.5GHz G4 Powerbook, which are running at the higher rate (approx 3.6Mb), so that proves that the signal speed is getting through, but just not at the same speed for the two iMacs??

Fuller picture at:

http://discussions.apple.com/thread.jspa?threadID=647469&tstart=0

I just had my Motorola 5101 replaced with a 5120. The speakeasy test ramp straight up to 6mb now vs 1.5 or 2 and this is over an Airport connection via a Netgear wireless router. Time will tell if this speed stays constant

What does the Mac do differently with ethernet to cause the Broadcom chips to reduce the throughput?

Kelvin

This Cisco document discusses some issues with a Broadcom chip and cable modems, though it seems to be limited to unstream issues.

Still, it's pretty interesting.

Broadcom guy/gal, is this the root of the problem you've described?

http://www.cisco.com/en/US/tech/tk86/tk319/technologiestechnote09186a008012fb28.shtml

Thanks to all of you for this thread. Especially Broadcom and Karl Wojcik.

I have been using a Netgear RT314 (old model, I know) with a Time Warner supplied RCA DMC425 cable modem for several years without any problems. I also had added a Netgear Wireless Access Point (ME102) a few years back. When I upgraded to OSX 10.4.8 a few weeks ago, I started experiencing internet connection slowdowns, both wired and wireless. I kept re-booting the cable modem and computers and would only occasionally get my speed back.

I then searched for help and found this thread. Based only on my experiences and the information and suggestions in this thread, specifically the input from Karl on his speed improvements, I purchased a new cable modem (the Motorola SB5120) and a new router (Netgear FVS114).

Here are the speed improvements I am now enjoying, based on the speakeasy website speed tests:

Old setup - RCA DMC425 cable modem, Netgear RT314 router

Download = 50 kbps; 6.3 KB/sec transfer rate
Upload = 468 Kbps; 58.5 KB/sec transfer rate

New setup - Motorola SB5120 cable modem, Netgear FVS114 router

Download = 7536 kbps; 942 KB/sec transfer rate
Upload = 464 Kbps; 58 KB/sec transfer rate

These new speeds equate to a 7.5 Mbps rate. Since I also recently upgraded my Roadrunner account to a premium speed, hoping that this would solve my problem, which it didn't, I am now getting close to the 8 Mbps that I am paying for.

My old speeds shown above were after 10.4.8, and I was getting better speeds with 10.4.7, but my internet connection is now fast, responsive, and as advertised. This not only affects Safari and Mail, but my Quicken usage. Obviously, this should also affect my iWeb updates, iTunes downloads, Apple software updates, etc.

Whenever I have Apple related problems (and I have been fortunate to have only a few), I come to these boards for suggestions. I can't think of any problem I have had that has not been resolved here. And none with the dramatic affects shown by the speed tests above.

Thanks again to Broadcom and Karl for sharing your firsthand knowledge of the issues affecting our Macs, and the rest of you who, with the proper amount of caution and skepticism, helped to confirm that the comments in this thread were legitimate. I can't thank you all enough for your help.

This community definitely helps to make the already awesome Mac experience even that much more satisfying.

Happy Surfing!

Santiago

Everyone please note there is a problem with Mac OS X 10.4.8 and third party utilities such as CoconutWiFi (which purports to have a workaround for the problem, but at least on my MBP C2D does not), and dashboard widgets such as Airport Radar, AirTraffic Control, etc. I'm not sure about JWire.

You can easily see the problem by just going to a terminal command line and entering PING xxx.xxx.xxx.xxx where xxx.xxx.xxx.xxx is the IP address of your wireless router. In my case, while sitting 5 feet from my WAP, about every 4-5 pings the delay would increase significantly, then drop back down to normal for a few and then repeat. When I quit CoconutWiFi the problem disapeared.

I have since removed CoconutWiFI from my login items and made sure that no dashboard airport widget utilities are loaded and restarted my system. Everything is now running great.

I am not saying there aren't MBP wireless problems (there are other threads about this), nor am I saying that the Broadcom chip issue isn't real. In fact, I replaced my Motorola 5100 with a Docsis 2 D-Link router and performance on my wired computers is SIGNIFICANTLY faster, so I'm a believer.

I am just pointing this out to everyone so that you're not diagnosing a problem that is masked by an MBP wireless issue (if you're wireless that is) that may or may not be real.

Hope this helps everyone. I have found this thread helpful and wanted to help others.

I do think it has something to do with DOCSIS, yet I know next to nothing! 🙂

Do you mind if we ask which modem you use?