Airport Extreme FE918LL/A Model A1521

I bought this model refurbished from Apple about three months ago. This model is suppose to be 802.11ac. If I go to System Report>Network>Wi-Fi>Interfaces>Supported PHY Modes, the highest supported Mode shows 802.11n.


Why wouldn't ac be shown as a supported mode.

iMac (21.5-inch Late 2009), OS X El Capitan (10.11), iPhone, iPad, Apple TV, Airport

Posted on Feb 26, 2017 10:33 AM

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8 replies

Feb 26, 2017 11:08 AM in response to Bob Timmons

I'm checking the system Report with my late 2009 iMac which I know is not n/ac capable. The only client connected at the moment is the latest Apple TV4. From Apple TV Settings, I can't find anywhere in the setting options which says the GHz I'm connected to or if it's connected to ac. I have two iPhone clients that are ac capable but they are away at the moment.


I've included a screenshot of my Airport Utility Wireless Options.

User uploaded file

Feb 26, 2017 2:34 PM in response to Joe Gramm

And, as you can see, the Apple TV is indeed receiving an impressive signal speed of 702 Mbps.......so "ac" speeds are being broadcast by the router and received by the Apple TV.


So,the PHY Mode of the connection indicates that signals are being broadcast at "a" levels, "n"levels and "ac" levels. 802.11a/n/ac


But....while this is impressive, the Apple TV internal processor is limited to 100 Mbps speeds.....so, while it can technically "receive" a speed of up to 1300 Mbps, it can only process signals at up to 100 Mbps levels. That's why the Ethernet port on the Apple TV is 100 Mbps.....not 1,000 Mbps like the Ethernet ports on the AirPort Extreme.

Feb 26, 2017 10:46 AM in response to Joe Gramm

Several reasons......


  • The wireless device that you are using might not support 802.11ac (If you are asking about the iMac listed in your profile, that product would not support 802.11ac)
  • The wireless device is connecting to 802.11n using the stronger 2.4 GHz signal
  • The wireless device might be located too far from the router to pick up the much weaker 5 GHz "ac" signal


With a few more specifics, we might be able to provide a bit more feedback. Things like......


What device are you using now to check the connection?

What Channel is the current wireless connection using?

Is the wireless device connecting using 2.4 GHz or 5 GHz?

Do you have a separate name assigned to the 5 GHz network?

Do other devices connect at "ac" levels?

How close to the router is the wireless device?

Feb 26, 2017 2:48 PM in response to Joe Gramm

As it stands now, you have not assigned a separate name to the 5 GHz band on your AirPort router, so wireless clients will connect to either 2.4 GHz or 5 GHz depending on their own capabilities and distance in relation to the router.


Unless the Apple TV is located in the same room as the AirPort router, or you have close to a line-of-sight relationship between the Apple TV and the AirPort router, the Apple TV will likely connect to the stronger 2.4 GHz signal, even though the 5 GHz "ac" signal might be a faster connection.


Open AirPort Utility

Hold down the option key on your Mac while you double click on the picture of the AirPort router

Wireless Clients will appear

Click on the arrow next to each connected wireless client for more information about that device


Post back with the info that you see displayed for the Apple TV connection

Feb 26, 2017 2:48 PM in response to Joe Gramm

No as far as the Apple TV is concerned since it is already connecting at "ac" levels.


Possibly, if you have other "ac" capable devices that are not in close proximity to the AirPort Extreme and you want to force them to try to connect at "ac" levels.


But....while you can try to "force" a device to connect at "ac" levels, if the device is not close to the router, then chances are the 2.4 GHz connection will still be faster than the 5 GHz connection at that location and you already know that the 2.4 GHz signal will be stronger.


Remember that 5 GHz "ac" signals are much weaker than 2.4 GHz signals, so the fact that a device might connect at "ac" levels does not mean to imply that this would be a better connection than the stronger 2.4 GHz signal.


Only when an "ac" device is in close proximity to the router will "ac" be of any real benefit.

This thread has been closed by the system or the community team. You may vote for any posts you find helpful, or search the Community for additional answers.

Airport Extreme FE918LL/A Model A1521

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