Q: wifi with Yosemite

Hi ..

Might be corrupted network preferences as a result of the upgrading.

Open the Finder. From the Finder menu bar click Go > Go to Folder

Type or copy paste the following:

/Library/Preferences/SystemConfiguration

Click Go then move all the files in the SystemConfiguration folder to the Trash.

Restart your Mac.

See if that makes a difference.

Your Mac will generate a new SystemConfiguration folder for you.

If that doesn’t help, try here >  Wi-Fi: How to troubleshoot Wi-Fi connectivity

There are definite bugs in Yosemite that need to be addressed by Apple. Multiple people are experiencing Wifi issues with fresh installs of Yosemite. 

I was experiencing consistent Wifi issues after a fresh install of Yosemite.  I validated that it wasn't my computer or router by doing a fresh re-install of Mavericks.  Wifi works flawlessly under Mavericks but always fails under Yosemite. No other software was installed as part of this test.

Here is my configuration:

Model Name: MacBook Pro

  Model Identifier: MacBookPro8,1

  Processor Name: Intel Core i5

  Processor Speed: 2.4 GHz

  Number of Processors: 1

  Total Number of Cores: 2

  L2 Cache (per Core): 256 KB

  L3 Cache: 3 MB

  Memory: 10 GB

  Boot ROM Version: MBP81.0047.B27

  SMC Version (system): 1.68f99

  Serial Number (system): C2QGV006DVHJ

  Hardware UUID: XXXXX

  Sudden Motion Sensor:

  State: Enabled

So I had the same problem with my '13 MBA.

It's impossible to use/work with the constant WIFI drop off & this is my primary work laptop. None of my coworker on MBP/MBA had this problem.

I've installed this on my '08 MacBook & '10 MBP both without WIFI issue though it slow the system down dramatically.

I've tried all the suggest fix I can find on Google without success.

I a fit of rage, I reinstall the Yosemite again instead of throwing the MacBook Air out of the window. It's been 24 HR and so far WIFI seems to hold up.

Safari did always pause momentarily before proceeding. Probably due to the proxy.

Will report again in the next few day of field testing.

Seems like OS X is going down the MS Windows' path of reliability doom.

Nope I still get WIFI dropping.

I've updated to 10.10.1 a moment ago. Upon reboot, my WIFI drop off, reconnect and drop off again several time.

10.10.1 update don't solve the WIFI drop out issue for me.

May have to revert back to maverick as last resort.

This is getting ridiculous.

I updated yesterday ('13 MBP), which is when my WIFI started to disconnect intermittently. Before that, I had no issue.

I created a new network location and deleted Bluetooth DUN.  Have not had any wifi problems since.

(MacBook Pro 13-inch, Mid 2012 Mac 10.10 Yosemite)

I have the same problem. Since updating Yosemite yesterday I cannot connect to my wifi- therefore no internet and mail. I have a MacPro. Did the fix on Nov. 12 work for you?

No, the Nov 12 OS X 10.10.1 did not fix or make any difference for my case. I'm not sure if it works for other.

I'm using good old wired LAN cable for now at work until a solution is release.

I have been having the wifi problem also. I downloaded the update and it made no difference. Then yesterday I decided to try re-loading Yosemite from the App store. It loaded the latest version just as if I had never loaded it before (took about 20 minutes). Miraculously the problem has stopped, and I have had continuous wifi connection for the last 24 hours (longest since upgrading to Yosemite). Fingers crossed it continues.

Wish you luck PegVox. Let us know if the problem goes away after a week of field testing.

I did the same but it did not work for long term. When it start dropping off the problem begins. 

I'm hook up on LAN cable at work for now.

What is very interesting to me after examining the myriad latest forum threads about OSX 10.10.1 and WiFi issues is that it all boils down to one obvious problem: OSX 10.10 Yosemite is optimized for Apple routers such as Airport Express and Time Capsule, that are running the very latest WiFi 802.11ac
Most of the forum posters here neglect to state the third party routers they are currently using when they post of serious Yosemite WiFi problems
Clearly many folks own or rent older third party routers that are now incompatible with Yosemite. But no big deal. Just get a standard cable modem only from your internet phone/cable service provider, and plug the cable modem ethernet output into a newly purchased Apple router 802.11ac ethernet input port. Then reconfigure your system to your needs. The major problem here is that the internet providers (ATT, TWC, etc) are providing outdated routers to customers that are obsolete and will never be able to upgrade to Yosemite.

This is not practical at all. I can't ask my company to change their router or the provider of free WIFI in the shops or airport to upgrade to 802.11AC.

Infact I don't belief its the router issue. My coworker all with MacBook Pro/Air did not have the issue I had after upgrading theirs to 10.10. Similarly my older MacBook & MacBook pro did not suffer from this WIFI dropping after upgrading. I had a Time Capsule and running on 802.11n 5Ghz. The drop out rate at home for me were far lower but once it drops, I can no longer reconnect as it kept dropping. Of course it will recover itself. how? why? I don't know. Reboot doesn't seems to have any effect. 

I don't know the root cause of the problem so won't speculate. It has been a nightmarish experience.