Internet periodically stops working on one Mac but not another

[ConnectivityIssues]

I have two macs right next to each other on my workstation. One is a 2010 MacBook Pro and the other is a 2011 iMac. Both are connected to the same router via wifi. I also have an iPhone that's connected to the same router.

The iPhone's connectivity is fine. The MacBook's is fine. The iMac's however is not. On the iMac I experience constant packet loss and consistent steep dips in speeds. I use the iMac for graphically intensive stuff (mostly gaming) so that packet loss is really easy to feel. I know the MacBook doesn't experience that packet loss since I use it for watching videos and doesn't drop the quality or the downloads like the iMac does.

Running speed tests also show a stark difference between the two. The MacBook gets about 9/1 mbps download/upload while the iMac gets 3/3.5 mbps download/upload on the same speed test ran concurrently. Going to the network diagnostics on both, the packet loss differential is also confirmed, with the iMac sometimes dropping no packets, and others, every packet.

I searched around for many hours and have no good idea on how to fix this. The only idea I got left is to just connect the iMac with the MacBook with an ethernet cable and try to share the wifi from the MacBook. However, I did read somewhere that that would chew through the lifecycle of the MacBook so I'm hesitant to come to that. Any help on this matter is appreciated.

 

[hobowankenobi]

Hey -

So for the iMac, it is likely one of two things:

Software: OS update/reinstall, or booting from an external drive with a fresh OS could help prove (or disprove) this. Outside change there is some third party software that might cause some issues. Both of these seem unlikely.

Hardware: Something is not right with the radio and/or antenna in the iMac. If it has ever been opened for say, a hard drive replacement or upgrade, it is possible that the antenna was damaged or disconnected, or perhaps moved to where some shielding is cutting signal. As it is an older machine, could be limitations of the radio or antennas. Not all machines perform the same. Seems unlikely though, that the older MBP should do so much better.

Outside chance there is something going on with your wifi...such as a dead spot, shadow, or other shielding/interference. There are some diagnostic software tools that can show signal strength a Mac. Also seems unlikely as other devices in the same area seem to not suffer the same problems.

Any chance the MBP is interfering with the iMac? Does the iMac perform any better if the MBP is removed from the area? How about moving the iMac around to see if the performance is equally poor, at other (similar distance) locations?

If, with more testing, it seems that the iMac has generally poor wifi performance and it is most likely a hardware problem, it may be possible to repair any damage. But rather than risk some fairly major surgery, you might also consider a wifi adapter that is the entire radio and antenna. Something like this. Keep in mind that for most add-on wifi devices, one must install the drivers for it to work.

 

[BrianBaughn]

What are the results when only one-device-at-a-time is powered on?