Why does my Mac Pro lose internet (while iTunes still streams)?

April 13, 2017 10:24 AM

Mac help needed: A few times a day, my Mac Pro loses internet access - here's what Network Status looks like - and Web browsing is impossible. Strangely, any stream I have running on iTunes continues to play, with no interruption, until the connection is fully restored about 5 minutes later. But the plot thickens...

Whenever the Mac Pro goes down, other nearby devices, like a MacBook Air and iPhone, continue to enjoy uninterrupted connections (and all green lights on Network Status) on the same wifi network.

Does anyone know -

(a) why the Mac Pro would lose its connectivity a few times a day, while other devices are fine?

(b) why iTunes would continue to stream even when the "Internet" and "Server" lights are red?

My sense is that it has something to do with either the Mac Pro's IP address assigned by the router, or some DNS issue. But I'm not enough of an expert to know how to debug or address those issues.

posted by mark7570 to Computers & Internet (8 answers total)

Best answer: I'd agree about DNS (except, only one device losing partial internet whereas the others don't, doesn't quite agree with this). Try changing your DNS servers to google's or OpenDNS (theirs are 208.67.222.222 and 208.67.220.220; unfortunately their site doesn't easily show them to you now).

The fact that it only happens to the Pro is confusing, but it's possible that the other devices are using different DNS servers, I guess...
posted by destructive cactus at 10:40 AM on April 13, 2017 [1 favorite]

Is the Mac Pro plugged in to ethernet as well? My macs do odd network things when they have two routes to the internet. I tend to turn off my wifi when I plug in to avoid this problem.
posted by advicepig at 10:50 AM on April 13, 2017

Response by poster: @cactus - thx, will try it.

@advicepig - no, the Pro is on wifi-only connection, no ethernet.
posted by mark7570 at 12:33 PM on April 13, 2017

Best answer: On the off chance that this is related: For the last couple of weeks I've had a problem where my MacBook Pro slows to a crawl and I am unable to browse the web. When I go to Activity Monitor, I discover a process called Safari Networking that is using about 40 GB of mostly virtual memory. Upon killing it, all browser windows that are trying to access the internet instantly error out and then, just as instantly, are able to be reloaded and used as normal. No idea what's causing it, but it's only been happening to me recently.
posted by Polycarp at 1:23 PM on April 13, 2017

why the Mac Pro would lose its connectivity a few times a day, while other devices are fine?

I've had certain wireless cards in computers have issues like that with cheap wireless routers - everything else in the house would be fine but the problematic computers would lose access to the internet for a short period of time.

why iTunes would continue to stream even when the "Internet" and "Server" lights are red?

My guess would be that it's not streaming in realtime and has pulled down the entire file to the local cache and is just continuing to play that.
posted by Candleman at 2:33 PM on April 13, 2017 [1 favorite]

Best answer: My guess is DNS too. One way to test that theory; when the Mac Pro is acting like it's offline, open a terminal window and do ping 8.8.8.8. (Coincidentally that's Google's DNS server, but it also answers ping and is a good "am I online?" test.) If it's getting through then your basic Internet connection is fine and it's probably your DNS queries that are failing.
posted by Nelson at 3:51 PM on April 13, 2017 [1 favorite]

Response by poster: My guess would be that it's not streaming in realtime and has pulled down the entire file to the local cache and is just continuing to play that.

I thought that, too, but then I found that the stream kept up with the live-radio FM feed for several minutes (i.e., it was definitely streaming live, not playing a buffer).

I'll try the "ping 8.8.8.8" command to see if it's a DNS issue. "ping google.com" definitely fails during these outages but I haven't tried pinging the server address. (And, @Polycarp, I'll also check Activity Monitor - good idea.)

Thanks, everyone, and let me know if you think of any other possibilities.
posted by mark7570 at 6:34 PM on April 13, 2017

Response by poster: I had a technician visit today and, best I can tell, it was a voltage issue, of all things... voltage was too high entering the router, which caused all sorts of screwiness in the wifi signal. New attenuator pad installed - so far so good.
posted by mark7570 at 3:06 PM on April 14, 2017