WiFi keeps dropping requiring restart (confirmed non-hardware issue)

I have taken my late 2011 MacBook Pro to the 'Genius Bar' and they said that this was NOT a hardware issue as they ran the diagnostic and found no problems. This is why I am posting this despite there being many similar questions, as all of them were resolved by replacing the hardware. The Apple 'Genius' then said the WiFi was "probably" dropping because I was running Mountain Lion and Yosemite had lots of connectivity updates. I am now running Yosemite 10.10.3 but the problem persists.

The Problem

I'll be connected to any given WiFi connection (indicating this is not a router or channel problem) and everything will work fine. Within a period of time – normally ranging from a few minutes to an hour – I will try to load a web page and see its loading status say 'resolving host' (Chrome v43).

When the WiFi dies, the only (temporary) solution is to 'forget' the network, make WiFi service inactive and then remove the service altogether, before rebooting and re-activating it. When the WiFi dies, the signal icon shows a full strength connection and in 'System Preferences > Network' the button says 'Turn WiFi off' as though it hasn't realised yet.

Sometimes, when I boot back up, clicking on the WiFi icon shows a message stating 'No hardware detected'. I have to restart once or even a few times before this is fixed.

Attempted Solutions

• Called Apple support who talked me through deleting lots of different preference files
• Took to Apple Genius who said it was 100% not a hardware isse as this would be picked up in diagnostics
• Updated from Mountain Lion to Yosemite
• Updated all other software
• Reset PRAM / SMC

** Log **

01/06/2015 23:29:22.298 discoveryd[78]: Basic DNSResolver UDNS Send(): UDP Sendto() failed to DNSNameServer 194.168.8.100 Port 53 errno 65, fd 56, ErrLogCount 50 ResolverIntf:5
01/06/2015 23:29:58.329 com.apple.xpc.launchd[1]: (com.apple.CoreRAID[845]) Endpoint has been activated through legacy launch(3) APIs. Please switch to XPC or bootstrap_check_in(): com.apple.CoreRAID
01/06/2015 23:30:00.000 kernel[0]: Sandbox: fontworker(849) deny file-read-data /Library/Fonts/Summit_OpenType/SummitBold-InlineOne.otf
01/06/2015 23:30:08.000 kernel[0]: SerialATAPI device reconfiguration did not complete successfully.  (failedCommandInfo = 0x1)
01/06/2015 23:30:31.117 discoveryd[78]: Basic DNSResolver  Re-Binding to random udp port 50861
01/06/2015 23:30:33.191 com.apple.xpc.launchd[1]: (org.ntp.ntpd) Unknown key for Boolean: ForceEnableHack
01/06/2015 23:30:35.416 com.apple.preference.datetime.remoteservice[900]: Failed to connect (worldMap) outlet from (GEOCityPickerViewPrivController) to (GEOWorldTimeZoneView): missing setter or instance variable
01/06/2015 23:30:42.181 WindowServer[146]: WSGetSurfaceInWindow : Invalid surface 753037142 for window 141
01/06/2015 23:30:42.181 WindowServer[146]: WSGetSurfaceInWindow : Invalid surface 753037142 for window 141
01/06/2015 23:30:42.181 WindowServer[146]: WSGetSurfaceInWindow : Invalid surface 753037142 for window 141
01/06/2015 23:30:42.304 com.apple.xpc.launchd[1]: (com.apple.preference.datetime.remoteservice[900]) Service exited due to signal: Killed: 9
01/06/2015 23:31:03.337 matt[907]: Unable to resolve hostname(s)
01/06/2015 23:31:21.066 com.evernote.EvernoteHelper[800]: Terminating in response to shutdown notification
01/06/2015 23:31:31.072 CoreServicesUIAgent[301]: unexpected message <OS_xpc_error: <error: 0x7fff7775dc60> { count = 1, contents =
    "XPCErrorDescription" => <string: 0x7fff7775df70> { length = 18, contents = "Connection invalid" }
}>
01/06/2015 23:31:33.463 ntpd[901]: drift PPM:0.000 -> -48.093
01/06/2015 23:32:04.000 kernel[0]: Google Chrome He (map: 0xffffff803bef40f0) triggered DYLD shared region unnest for map: 0xffffff803bef40f0, region 0x7fff95000000->0x7fff95200000. While not abnormal for debuggers, this increases system memory footprint until the target exits.

I monitored my WiFi connection so I knew when it dropped and checked the console log. I have uploaded it to Github for you to look at. It's available here.

I am at a loss. This is severely affecting my work as a freelancer and my morale. If anyone has any ideas please do share. Thanks.

Solution 1:

I recently had similar issues with Macbook air keep dropping wifi and constantly searching wifi. I knew it was not because of my wifi router because my android device had stable connection. Upon trying different tricks such as restarting network etc, none seems to work. I finally came up with a temporary fix. I opened the network preference on Mac and ran the network diagnosis, it says my network is working fine. Then I close the network preference. And Viola, the network is now working just fine. It seems to me that some file or setting is corrupted in the network registry for some reason, and after running diagnosis, the OS overwrite and fix the corrupted file or setting until next time it is corrupted again. Hope that helps.