Fix? MacBook Air USB Ethernet

USB Ethernet Connected

I’ve got a 2010 MacBookAir3,1 — 1.6GHz Core 2 Duo — OS 10.6.8

I’ve had a terrible time getting my USB Ethernet adapter to work. Trouble both at home and at the office. Across 3 different adapters.

I’d get either of these messages:

“Self-assigned IP address”


“Ethernet is not connected”

After a couple of months of giving up entirely, I’ve done some research and have found a fix of sorts. Steps I took:

  1. In System Preferences > Networking …
  2. Created a new location, getting off the Automatic location
  3. Clicked the plus in the bottom left to create a USB Ethernet connection
  4. Under that connection, clicked the “Advanced …” button in the lower right
  5. Selected the Ethernet tab (farthest on the right)
  6. Edited the settings under that tab as follows:
    • Configure: changed from Automatically to Manually
    • Speed: 10baseT/UTP
    • Duplex: half-duplex
    • MTU: Standard

I’ll admit I don’t know what these settings do.

But suddenly my USB is recognized and works.

Though none supplied this fix, I gleaned ideas from these comments in Apple support pages, some of which led me in this direction.

Seems utterly strange to me that there are no published fixes rolled into Apple updates.

2 thoughts on “Fix? MacBook Air USB Ethernet

  1. Well, it looks to me like you’ve discovered that the auto configuration code isn’t working. You might want to take a look at this driver – especially if you’re trying to use the adapter with anything other than a MacBook Air. It used to work on the Mac Mini, but not on 10.6.8 (the latest version of Snow Leopard). The manual configuration trick does appear to work with Snow Leopard.

    The way you’ve set up the adapter you’re going for the lowest common denominator. If you’ve got a switch or a hub that will run at 100 Mbps (100baseTX you might want to experiment with the speed and duplex settings (full or full with flow control). You should probably leave the MTU where it was set (standard 1500). You may be able to improve performance.

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