My Mac kills my DSL connection - why?
January 15, 2012 8:25 AM Subscribe
My Mac kills my DSL connection - why?
I posted a question about my DSL issues a week ago but have since isolated the problem to a specific issue with my Mac.
My DSL connection works fine so long as my MacBook Pro (Lion, all updates) is not connected to the network.
I have an Actiontec GT724WGR DSL modem and AT&T DSL service. I usually access the network over wifi (built into the Actiontec). When I use a PC laptop, everything works fine. But when I connect my MacBook to the Actiontec, the DSL connection usually slows way down. If I am running a repeating ping on the PC, I usually see a huge slowdown the minute the Mac comes on line (20ms pings to 1200ms). Taking the Mac offline immediately fixes the problem – the pings on the PC immediately speed up. This happens whether the Mac is connected by wifi or by Ethernet to the Actiontec. The slowdown happens even if I am not using the Mac to do anything – i.e., I am not running a browser or anything on the Mac; just connecting the Mac seem to screw everything up.
To make it a little more mysterious – sometimes (like 2 out of 10 times) connecting the Mac does not immediately cause a problem. Sometimes everything works for a while (5 min to 30 min) before the slowdown occurs. During that window, I can use the Mac web browser at full speed. Eventually, though, it slows down. Sometimes I can fix the slowdown for a while by power cycling the DSL modem, but eventually it slows down again. The problem is always cured immediately by taking the Mac offline.
I’m starting to think that there is just some incompatibility between the Actiontec and the Mac and/or Lion. But I hate to buy a new DSL modem and have the exact same thing happen.
I have tinkered with all of the Mac's "network" settings without any result, including deleting and reentering Wifi info. One possible relevant issue is that I know AT&T DSL runs over PPoE, but I have not set up PPoE on the mac. I think the DSL modem handles the PPoE and I don't need to configure it on the Mac, but perhaps I am wrong. I have tried to set up PPoE on the Mac, but I get an error "can't find PPoE server." I think this may be a red herring, though, because I never set up PPoE on the PC and it works fine.
I posted a question about my DSL issues a week ago but have since isolated the problem to a specific issue with my Mac.
My DSL connection works fine so long as my MacBook Pro (Lion, all updates) is not connected to the network.
I have an Actiontec GT724WGR DSL modem and AT&T DSL service. I usually access the network over wifi (built into the Actiontec). When I use a PC laptop, everything works fine. But when I connect my MacBook to the Actiontec, the DSL connection usually slows way down. If I am running a repeating ping on the PC, I usually see a huge slowdown the minute the Mac comes on line (20ms pings to 1200ms). Taking the Mac offline immediately fixes the problem – the pings on the PC immediately speed up. This happens whether the Mac is connected by wifi or by Ethernet to the Actiontec. The slowdown happens even if I am not using the Mac to do anything – i.e., I am not running a browser or anything on the Mac; just connecting the Mac seem to screw everything up.
To make it a little more mysterious – sometimes (like 2 out of 10 times) connecting the Mac does not immediately cause a problem. Sometimes everything works for a while (5 min to 30 min) before the slowdown occurs. During that window, I can use the Mac web browser at full speed. Eventually, though, it slows down. Sometimes I can fix the slowdown for a while by power cycling the DSL modem, but eventually it slows down again. The problem is always cured immediately by taking the Mac offline.
I’m starting to think that there is just some incompatibility between the Actiontec and the Mac and/or Lion. But I hate to buy a new DSL modem and have the exact same thing happen.
I have tinkered with all of the Mac's "network" settings without any result, including deleting and reentering Wifi info. One possible relevant issue is that I know AT&T DSL runs over PPoE, but I have not set up PPoE on the mac. I think the DSL modem handles the PPoE and I don't need to configure it on the Mac, but perhaps I am wrong. I have tried to set up PPoE on the Mac, but I get an error "can't find PPoE server." I think this may be a red herring, though, because I never set up PPoE on the PC and it works fine.
Best answer: Is the Mac running PhotoStream and is it where you store your pictures? PhotoStream does a hefty chunk of uploading, and uploading tends to swamp the ability for TCP ACKs to get through, which makes everything get much much slower. Mac goes off the network and the uploading stops, and ping times return to normal. Mac comes back on the network and it takes a while to determine that it can start uploading again, and once it does, the ping time goes to hell again.
posted by Kyol at 8:32 AM on January 15, 2012
posted by Kyol at 8:32 AM on January 15, 2012
Response by poster: Yes on PhotoStream - but does that run in the background? Because this happens even when iphoto is not up.
posted by Mid at 8:34 AM on January 15, 2012
posted by Mid at 8:34 AM on January 15, 2012
I'm not 100% sure - I know that PhotoStream only seems to download in the foreground, but I'm not absolutely certain if it uploads in the background after you quit iPhoto. I tend to take pictures on my iPhone, so they go up through that and not iPhoto.
posted by Kyol at 8:36 AM on January 15, 2012
posted by Kyol at 8:36 AM on January 15, 2012
I don't know, but provider-provided DSL modems with Wifi are often quite terrible. I have had all sorts of problems and you don't usually have the ability to make the necessary changes.
PPPOE is a way to connect to the network over DSL, you might have to program if it was just a modem, but it sounds like your router is programmed for PPPOE already. In fact, you should make sure that it's only your router trying to do this, and not other computers in your house as well.
Also, you are saying that the PC is fine when connected (Wirelessly?) and then you connect the Mac (Wirelessly) and it slows down? What if you had just the Mac connected?
posted by Napierzaza at 8:45 AM on January 15, 2012
PPPOE is a way to connect to the network over DSL, you might have to program if it was just a modem, but it sounds like your router is programmed for PPPOE already. In fact, you should make sure that it's only your router trying to do this, and not other computers in your house as well.
Also, you are saying that the PC is fine when connected (Wirelessly?) and then you connect the Mac (Wirelessly) and it slows down? What if you had just the Mac connected?
posted by Napierzaza at 8:45 AM on January 15, 2012
Best answer: The most important question to answer is how much bandwidth your Mac is using. Launch Activity Monitor (It's in /Applications/Utilities), click the Network button at the bottom, and look at the little graph. If your Mac is sending or receiving more than, oh, 100KB/sec in a sustained way, then some program is using a lot of bandwidth. If you follow up here, a screenshot of the network stats would be helpful.
Unfortunately there's no easy way on a Mac to find out which program is using all that bandwidth. The process that's using a lot of CPU (as seen in Activity Monitor) is a good bet. Or look at what's running and try to guess. Obviously BitTorrent could be the culprit, if you're running it. So could any network backup you have enabled. Maybe even iCloud sync?
A better router may allow you to use network intensive programs more reliably. I'm unfamiliar with your DSL modem/router, but it looks to be about 2008 vintage. By that time most router manufacturers were fixing the worst bugs in their software so I'd hope it would handle heavy load well, but you never know.
posted by Nelson at 9:36 AM on January 15, 2012
Unfortunately there's no easy way on a Mac to find out which program is using all that bandwidth. The process that's using a lot of CPU (as seen in Activity Monitor) is a good bet. Or look at what's running and try to guess. Obviously BitTorrent could be the culprit, if you're running it. So could any network backup you have enabled. Maybe even iCloud sync?
A better router may allow you to use network intensive programs more reliably. I'm unfamiliar with your DSL modem/router, but it looks to be about 2008 vintage. By that time most router manufacturers were fixing the worst bugs in their software so I'd hope it would handle heavy load well, but you never know.
posted by Nelson at 9:36 AM on January 15, 2012
Response by poster: Thanks - will check network activity in a bit. I do have the various iCloud backup and stream things turned on - maybe one is out of control.
posted by Mid at 9:49 AM on January 15, 2012
posted by Mid at 9:49 AM on January 15, 2012
My MacBook Pro (also Lion, also all updates) does something similar, but only when using BitTorrent. Opening a torrent on it will cause the entire network to slow way down, even for people using Windows PCs. I have yet to figure out what causes this, but I'm guessing that it's some sort of incompatibility between Lion and the terrible router/modem my ISP has saddled me with. Stopping the torrent on the MBP immediately fixes the problem.
Bittorrent uses a huge amount of bandwidth and also opens up a lot of connections, and most inexpensive routers will quickly use up their maximum number of connections if you're using bittorrent. You can fix both of those problems by installing dd-wrt on your router and then A) enabling QOS and setting bittorrent to bulk traffic and B) increasing the maximum number of simultaneous connections to 4096.
posted by empath at 9:53 AM on January 15, 2012
Bittorrent uses a huge amount of bandwidth and also opens up a lot of connections, and most inexpensive routers will quickly use up their maximum number of connections if you're using bittorrent. You can fix both of those problems by installing dd-wrt on your router and then A) enabling QOS and setting bittorrent to bulk traffic and B) increasing the maximum number of simultaneous connections to 4096.
posted by empath at 9:53 AM on January 15, 2012
Create a new user on your Mac, reboot the Mac, log into that new user and see if the DSL is slow or not.
If it is not show, you have a program running on your "real" user that is eat bandwidth.
posted by cowmix at 10:47 AM on January 15, 2012
If it is not show, you have a program running on your "real" user that is eat bandwidth.
posted by cowmix at 10:47 AM on January 15, 2012
Unfortunately there's no easy way on a Mac to find out which program is using all that bandwidth
It's been a while since I used it but I believe Little Snitch has a network monitor that will tell you this sort of thing.
posted by ook at 10:59 AM on January 15, 2012 [1 favorite]
It's been a while since I used it but I believe Little Snitch has a network monitor that will tell you this sort of thing.
posted by ook at 10:59 AM on January 15, 2012 [1 favorite]
Are you running dropbox on the mac?
Is it trying to download or upload?
posted by the Real Dan at 11:36 AM on January 15, 2012
Is it trying to download or upload?
posted by the Real Dan at 11:36 AM on January 15, 2012
Response by poster: Ah ha! Following Nelson's advice, I checked Activity Monitor and there was a steady 75k-100k/second network usage running for some background process. I killed the photostream agent and that dropped the usage way down. Ping times now normal with the mac online.
I'm holding my breath because I've had several false-dawn fixes, but this seems pretty good.
I had no idea photostream tries to sync your photos in the background - I thought it only ran when iphoto was active. And I guess they didn't program photostream to avoid eating your entire connection.
Fingers crossed . . .
posted by Mid at 12:52 PM on January 15, 2012
I'm holding my breath because I've had several false-dawn fixes, but this seems pretty good.
I had no idea photostream tries to sync your photos in the background - I thought it only ran when iphoto was active. And I guess they didn't program photostream to avoid eating your entire connection.
Fingers crossed . . .
posted by Mid at 12:52 PM on January 15, 2012
Response by poster: Just replicated the problem and the fix by launching iphoto, which launched photostreamagent. Network usage jumped to 90k/sec. Then killed photostreamagent and all is well.
posted by Mid at 12:56 PM on January 15, 2012
posted by Mid at 12:56 PM on January 15, 2012
Response by poster: So is there anyway to tell photostream to not be a hog, or do I just have to shut off photostream?
posted by Mid at 12:59 PM on January 15, 2012
posted by Mid at 12:59 PM on January 15, 2012
Glad you found the problem. One weakness of home Internet is if you saturate your network with uploads then downloads suffer too, in the way you saw.
If you're technically inclined there are various ways to fix this kind of problem. Some applications (like uTorrent) let you limit bandwidth, but I don't think PhotoStream does. You may be able to do it yourself by running ipfw, see for instance these notes, but that's a bit one-off and complicated. Personally I run a router with Tomato firmware and have enabled some basic traffic shaping and QoS abilities; giving priority to TCP ACK in the router is a big help.
The simple solution is probably to let PhotoStream do its thing overnight and hopefully it will finish. Presumably it's just copying all your photos up to the network and once it's done it will calm down (until you add more photos).
BTW, this discussion prompted me to spend about an hour looking into how to find out which application on a Mac is using bandwidth. As ook says, Little Snitch will do this but I don't think it does monitoring very well. So far I'm most impressed with Rubbernet, which does a solid job showing graphs of per-user and per-application bandwidth usage. It's €30 but the free trial is complete enough for a quick one time look.
posted by Nelson at 1:17 PM on January 15, 2012 [1 favorite]
If you're technically inclined there are various ways to fix this kind of problem. Some applications (like uTorrent) let you limit bandwidth, but I don't think PhotoStream does. You may be able to do it yourself by running ipfw, see for instance these notes, but that's a bit one-off and complicated. Personally I run a router with Tomato firmware and have enabled some basic traffic shaping and QoS abilities; giving priority to TCP ACK in the router is a big help.
The simple solution is probably to let PhotoStream do its thing overnight and hopefully it will finish. Presumably it's just copying all your photos up to the network and once it's done it will calm down (until you add more photos).
BTW, this discussion prompted me to spend about an hour looking into how to find out which application on a Mac is using bandwidth. As ook says, Little Snitch will do this but I don't think it does monitoring very well. So far I'm most impressed with Rubbernet, which does a solid job showing graphs of per-user and per-application bandwidth usage. It's €30 but the free trial is complete enough for a quick one time look.
posted by Nelson at 1:17 PM on January 15, 2012 [1 favorite]
Response by poster: One side note with respect to Little Snitch - I installed it on a prior machine about 3-5 years ago and came to regret it because it was hard to uninstall and kept popping up with unwanted processes. This was a few years ago, it may be better now.
posted by Mid at 1:28 PM on January 15, 2012
posted by Mid at 1:28 PM on January 15, 2012
What happens if you let photostream go overnight and finish whatever it is doing?
posted by gjc at 4:10 PM on January 15, 2012
posted by gjc at 4:10 PM on January 15, 2012
This thread is closed to new comments.
Crucially, I can torrent to my heart's content on other people's networks, like if I'm visiting a friend's house. I also have a problem at home with the MBP not reconnecting to my home network if I wake it from sleep, which again does not happen elsewhere. Clearly, it's just not playing well with my router.
You may want to ask around to see if there are any router and modem combinations that are definitely known to work with a MBP, but other than that, I'm not sure if there's much you can do about it. Lion seems to have some weird issues when it comes to wifi, and so far Apple has shown no sign that they're going to fix them or even acknowledge their existence.
posted by anaximander at 8:31 AM on January 15, 2012