Stumped about sudden Network Problem in OS X Leopard

5 replies [Last post]
tmtomh's picture
Joined: Dec 20 2003
Posts: 568

Hi all,

Hoping someone can help me figure out what I'm missing:

- Web sites slow to load (iMac C2D, 2.8GHz, 4GB RAM, all browsers)
- Cable internet connection speed very fast - i.e. downloads are 300kb-1Mbps, very speedy
- Speed test sites (, Speakeasy, confirm very fast download speeds
- BUT - same speed test sites totally fail when doing upload tests - the test page hangs without doing the upload

- Turning IPv6 off in Network Prefs
- Turning Firewall off in Security Prefs
- Turning "reject anonymous pings" off in my router (Linksys WRT54G)
- Uninstalling Parallels Desktop (it seemed to add virtual network ports that were always on; they're now gone)
- Rebooting router
- Rebooting cable modem
- Rebooting iMac
- Using OpenDNS for DNS resolution
- Not using OpenDNS

I'm not a system or network admin, but I'm pretty knowledgeable about this stuff, and I'm completely stumped.

In the past, slow DNS resolution has been because of Comcast's servers, and switching to OpenDNS has immediately solved it.

But not this time - it just seems to take too long to initiate downloading from any domain.

I suspect that the sudden inability to do upload speed tests is related to my problem, but I don't know what the actual problem could be.

Any ideas?


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Eudimorphodon's picture
Joined: Dec 21 2003
Posts: 1204

You know of course that cable internet is nearly the worst technology out there when it comes to oversubscription, right? There could just be as simple as a couple bad apples on your local loop running Bittorrent servers.

Comcast in particular has a pretty shady reputation for overselling their uplink capacity. They've also been playing all sorts of games with automated "congestion management" technology lately, in an attempt to compensate for the FCC ordering them to leave peer-to-peer traffic alone.


tmtomh's picture
Joined: Dec 20 2003
Posts: 568
Hi Eudi, Thanks for this i

Hi Eudi,

Thanks for this info - you've provided some additional details to what I've been suspecting. I am on the warpath with Comcast and will not rest until my service works right (and I have a big fat credit from them on my account)!


tmtomh's picture
Joined: Dec 20 2003
Posts: 568
Update - Fixed

Fortunately I have a neighbor who's pretty high up in Comcast and he got my case escalated.

He doesn't know exactly what they did, but they changed something on the back end, and my upload speed went from 9kbps to 1,900kbps. (Yes, you read that right - it was so slow it was 9kbps and now it's more than 200 times faster since they did whatever they did.)

I've been a Comcast customer for 16 years and I can think of no more than 2 cases (out of a several dozen over the years) where my equipment or wiring had anything at all to do with the problem. It's always their network infrastructure that's messed up. Ugh.

Fortunately all appears well now - fingers crossed!


tmtomh's picture
Joined: Dec 20 2003
Posts: 568
Wonder of wonders - they repl

Wonder of wonders - they replaced the entire node for my area today. What a shock.

At least I know I wasn't crazy....

Dr. Webster's picture
Joined: Dec 19 2003
Posts: 1688
Qwest recently trenched fiber

Qwest recently trenched fiber in my neighborhood, and now offers 30Mbit Internet access over it. As soon as they get IPTV rolled in, I'm giving Comcast the boot. Those jokers have even started encoding some of the local broadcast HD channels, including the PBS station -- so you have to have a HD cable box (which they, naturally, charge extra for) just so you can watch those channels in HD, which you could otherwise pull off the air for free.


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