Why is my DSL connection so much worse on my Mac?
January 8, 2012 7:46 AM   Subscribe

Why is my DSL connection so much worse on my Mac?

I have a pretty crummy DSL connection from AT&T. It's supposed to be 1Mbps or something like that, but I get about 300-400kbps on those speed test sites. It's not great but, historically, it's been OK for our uses.

But - something happened recently that seems to have degraded the speed/performance of the connection when using my home computer (a MacBook Pro with newest version of Lion). The strange thing is, the performance seems much better on my work PC laptop, which I sometimes bring home (a Thinkpad with Win 7).

The main problem on the Mac is that I get these incredibly long "waiting for google.com" type messages at the bottom of the browser screen when trying to load a page. It just sits there, seemingly loading nothing and just "waiting" for a site to respond. This seems to be true in both Chrome and Firefox, though Chrome seems worse. Trying to load google is especially bad - it can "wait" for 2 minutes waiting for the google homepage to load.

What's weird is that if I interrupt the "waiting" phase with the "stop loading" butting and hit "reload" a few times, this sometimes fixes the issue and causes the page to load. This makes me think that the problem isn't necessarily the speed of the connection, but something that makes the initial attempt to load a page from the Mac fail and hangup.

I have tried fiddling around with the Chrome settings about caching and predicting network use. The problem seems to show up in Firefox too, so I don't think that's the cure. I have also switched DNS servers on the Mac several times. The PC does much better using the same DNS as the Mac.

Any clues? Thanks
posted by Mid to Computers & Internet (14 answers total) 7 users marked this as a favorite
Response by poster: Sorry - "stop loading button" above.
posted by Mid at 7:52 AM on January 8, 2012

Response by poster: Also - to be clear - Mac and PC are routing through the same wifi/dsl modem.
posted by Mid at 7:53 AM on January 8, 2012

This might help. It sounds as if you have something misconfigured on your Mac.
posted by blob at 8:12 AM on January 8, 2012

Could the dns settings be different?
posted by HuronBob at 8:46 AM on January 8, 2012

Yeah, I'd say your DNS server is not correct, so it's failing to resolve www.google.com or whatever. Open System Preferences / Network and lok at DNS Server. Does it look reasonable? In any event, try changing your DNS servers to and; those are Google's public servers and work very well. You can do this via the "Advanced" button in lower right, write back here if you need more guidance.
posted by Nelson at 8:49 AM on January 8, 2012

These detailed instructions from Google on configuring DNS may be of help.
posted by Nelson at 8:50 AM on January 8, 2012

Response by poster: Thanks - I agree it seems DNS related, but I have changed to the google DNS servers on the Mac - no dice. Flushing any local DNS cache seems promising.
posted by Mid at 8:54 AM on January 8, 2012

Is it definitely the DSL connection having problems, and not, eg, your mac's connection to the network? Are you using wifi? I've had routers in the past which seemed to have trouble maintaining reliable connections to macs, while PCs in the house were fine. Googling various forums suggested this could be a combination of one or more of: dodgy router firmware, dodgy airport, or weird tricks that OS X plays to try to speed up DHCP.

Anyway: try opening a Terminal window and pinging your DSL router - if there's a sudden rise in ping times or you start seeing dropped packets then the problem might be with the mac <-> router connection.
posted by doop at 10:44 AM on January 8, 2012

Response by poster: Totally embarrassing, but I found the problem. I forgot that about 2-3 weeks ago, I tried to clean up a tangle of wires and cables on the counter where the DSL modem sits. I replaced the phone cable that runs from the wall jack to the DSL modem with a super-short cable that I bought at a Home Depot-type store for $2. Swapping out that cable with some old crummy phone cable I had in the closet has fixed the problem. I guess the $2 cable was noisy, which was degrading speed and causing dropped packets. Now I'm wondering if I should try to buy some kind of higher-quality phone cable to see if my speed gets even better (it's still pretty slow relative to DSL standards).

I thought of the phone cable idea after reading this site, which has some helpful pointers on DSL troubleshooting.

Hopefully this helps someone else in the future. Thanks, all.
posted by Mid at 10:58 AM on January 12, 2012 [1 favorite]

Response by poster: (To be clear, the $2 cable was hooked to a DSL filter, but it still wasn't working right.)
posted by Mid at 11:00 AM on January 12, 2012

Response by poster: I spoke too soon. The change of cable fixed the problem for about 1 day. No we are back to intermittent slowdowns. The cable seems not to matter. Swapping the cable randomly and resetting the connection repeatedly seems to fix things for a little while, then it slows down again. I'm thinking intermittent line noise causing the modem to sync to a slower speed.
posted by Mid at 8:18 PM on January 13, 2012

Response by poster: Don't know if anyone is still reading, but I have drastically narrowed down the location of the problem and need more help!

I just realized that the DSL works find on my PC so long as my Mac is off or disconnected from the wifi network. For example, rock solid repeating ping times of 20ms to on the PC when the Mac is out of the picture.

But - when I put the Mac on the network, there is sometimes (but not always) an immediate huge slow down in the ping times showing on the PC. The time to goes to 1000+ms and some packets drop. When the slow condition starts, it is immediately cured every time by killing the Mac's network connection. Occasionally, I can operate the Mac fine for a while without causing the slow down condition. I can't quite figure out what action on the Mac starts the problem, but killing the Mac always stops the problem. If I want to start the problem for test purposes, I just turn the Mac's wifi on and off a few times and eventually the slow down starts.

Note that all of the above holds true even if I am not running any kind of web browser or any other "visible" application on the Mac. (Maybe I am running something in the background that I don't know about.) That is -- it seems to be the presence of the Mac alone--not any application on the Mac--causing the problem.

Any clues? Thanks again.
posted by Mid at 3:44 PM on January 14, 2012

Does your Mac have the same IP address as your PC? That'll break everything in confusing ways. If you're using DHCP in the usual way that shouldn't happen, but it's worth checking.
posted by Nelson at 7:03 PM on January 14, 2012

Response by poster: Thanks - different IPs.
posted by Mid at 9:19 PM on January 14, 2012

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