We have an AirPort Extreme 6th generation in the office. It's providing 5 GHz and 2.4 GHz wireless networks, with different names:

AirPort Utility: Wireless tab: AirPort Utility: Wireless tab

AirPort Utility: Wireless options: AirPort Utility: Wireless options

Sometimes, when a device is on Brains 5GHz, it can't communicate with other devices on the network, but it's able to connect to the internet with no problems.

It doesn't happen all the times, but it happens pretty frequently. Once it's begun, the only resolution is to switch my devices to the 2.4 GHz network, at the cost of much worse wireless performance.

When I say my devices "can't communicate with other devices on the network", here's what I mean:

  • Can't print from MBP or iPad (airprint) to wired printer. Printer status says the printer is "not found".
  • Can't ssh/screen share to coworkers' computers.
  • Can't reach my dev web server on my computer from an iPhone/iPad (and other mobile devices).
  • Can't mirror to Apple TV — doesn't even show up on the Airplay device list.

If both devices are on the 2.4 GHz network, there are no problems. If even one of them is on 5 GHz and the AirPort is misbehaving, we can't communicate with them.

The behaviour makes me wonder if the AirPort is isolating clients from each other somehow, but I've gone through the settings and updated the firmware, and still have problems.

Is there something I can change in my setup to resolve these problems?

  • I have never quite figured this out but here is my educated guess. Do not specify a name for your 5GHz network. You Machines will choose the most reliable network themselves and you do not have to worry about that. If you want 2 different networks, you choose two different names. – CousinCocaine Feb 26 '15 at 13:43
  • @CousinCocaine We specified separate names because when they were the same, we got extremely poor performance. We wanted to force devices onto the 5 GHz network for the improved performance. Even when the above-described problem is happening, performance is great to the internet (outside the NAT). – mrb Feb 26 '15 at 14:09
  • 5GHz is not by definition faster than the 2.4 frequency. A lot depends on the amount of noise on that frequency. Because 5GHz is less common and because the penetration is worse than 2.4GHz you should expect that it is faster indeed. But your Apple machines should be able to notice this as well and switch automatically. Btw, which device is your DHCP host? Your apple router or your cable companies router? – CousinCocaine Feb 26 '15 at 15:15

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