Questionable Wi-Fi problem on MBP: how to analyse it?

Question

I can't all of the sudden turn on WiFi on my MBP. I have upgraded to Yosemite half a year ago and it was all working fine until today.

I tried some tips from this thread Can't turn on wifi on Mac OSX Mountain lion MBP 2012 like sudo ifconfig en# up(tried all numbers because I don't know which en is WiFi...

I also tried hard power off; restarted several times; removed WiFi interface, restarted and added it back. Nothing helped. After hard power off I saw it trying to connect to a network for few secs and then it stopped again...

ifconfig output for wifi device:

en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
    ether 60:03:08:97:7a:56
    nd6 options=1<PERFORMNUD>
    media: autoselect (<unknown type>)
    status: inactive

Console output after system startup:

31/01/15 22:46:33,000 kernel[0]: AirPort: Link Down on en0. Reason 8 (Disassociated because station leaving).
31/01/15 22:46:33,000 kernel[0]: AirPort_Brcm4360_P2PInterface::init name <p2p0> role 1
31/01/15 22:46:33,000 kernel[0]: AirPort_Brcm4360_P2PInterface::init <p2p> role 1
31/01/15 22:46:33,000 kernel[0]: AirPort_Brcm4360_P2PInterface::init name <awdl0> role 4
31/01/15 22:46:33,000 kernel[0]: AirPort_Brcm4360_P2PInterface::attachToBpf name <awdl0> role 4 successful attach to bpf type 147
31/01/15 22:46:33,000 kernel[0]: AirPort_Brcm4360_P2PInterface::init <awdl> role 4
31/01/15 22:46:33,686 airportd[30]: airportdProcessDLILEvent: en0 attached (up)
31/01/15 22:46:35,000 kernel[0]: AirPort: Link Up on awdl0
31/01/15 22:46:39,000 kernel[0]: AirPort: Link Up on en0
31/01/15 22:46:39,000 kernel[0]: AirPort: RSN handshake complete on en0
31/01/15 22:46:39,653 airportd[30]: -[CWXPCConnection performScanWithChannels:ssidList:legacyScanSSID:includeHiddenNetworks:mergeScanResults:maxAge:maxMissCount:maxWakeCount:maxAutoJoinCount:interfaceName:waitForWiFi:waitForBluetooth:token:priority:reply:]: !!! SCAN request received 0.0127 seconds after previous scan request from 58 (locationd)
31/01/15 22:46:39,000 kernel[0]: AirPort: Link Down on en0. Reason 8 (Disassociated because station leaving).
31/01/15 22:46:40,005 airportd[30]: _handleLinkEvent: WiFi is not powered. Resetting state variables.

Does anyone have any clue how to fix it?

I'd prefer a solution that doesn't include reinstalling my whole system.

Answer 1

Try following in your Terminal:

Manually connect to WiFi

Turn On

networksetup -setairportpower en0 on

Find

/System/Library/PrivateFrameworks/Apple80211.framework/Versions/A/Resources/airport scan

Connect

networksetup -setairportnetwork en0 WIFI_SSID_I_WANT_TO_JOIN WIFI_PASSWORD

It also shows it is using your Samsung as network provider, so turn it off first then check again if wifi comes on.

Answer 2

We have the same MBP if you have the 13" model. [Thankfully I have no issues yet.]

I guess you did not install anything weird on the system or messed up any setting etc. Based on this premise:

• First and foremost, which version of Yosemite are you using? It is known that some of the initial versions had some Wi-Fi connectivity issues/bugs. Make sure you are using the latest version, i.e. 10.10.2 currently.

• If problem still exists, you can try resetting the PRAM and SMC of your machine.

• You can also check the Wireless Diagnostics to see if you can get any extra info.

If none of these work, wait for another answer or go directly to Apple (or both).