There are people who use a BT Homehub who have a wifi issues after upgrading to Yosemite but, equally, there are some who have no problem at all. Adding to the difficulty in establishing whether or not there is an inherent Yosemite/Homehub issue is the multiplicity of Homehub versions in use.

Is anyone going to get of their rear ends and fix this.  Had enough.  This is possibly the worst release ever along with the patch that was supposed to fix it.  Amateurs!

Still after upgrading in October I cant use my wireless.  This laptop is only going to stand so much more punching.  It will be obsolete by the time you fix it or broken, and I wont be buying another.

Apple, you are incompetent.

I have this problem too - with a brand new machine. Last time I bought a new mac Time Machine stopped working and it took weeks to get a fix. Now I have a new computer and I can't use the internet. I am getting very annoyed with apple.

I'm not technically competent and therefore can't help, but just fyi I have a BT Homehub 4 and can connect OK to 5ghz, but for no more than a few minutes to 2.4 before it grinds to a halt. Mavericks was fine. Just wanted briefly to add my voice to the thread for weight of numbers. At times this issue has felt like the nearest (though not very near) I've been to being an addict... waiting for a fix... waiting for a fix... although in truth I only need to place my Mac near the router for it to choose 5.0 and start working again. In the Apple store the rep said post-Yosemite his Mac's wifi didn't work at his house but works at his girlfriend's place, and he had no idea why. Didn't seem like it was just a chat up line to get to stay over at her place.

Yes, understood

My BT HomeHub5a update:

Today I downloaded some advice from BT Infinity User Forum and made the following changes:

2.4 ghz switched from Channel 11 > 13  5 ghz from channel 44 to 40  (Forum user said these were likely to be least used)

Devices (iPhones, iPads and MacBook Pro havae all been able to connect INSTANTLY to both wavelengths - password was requested and accepted BTW a few days ago I made the passwords for the 2 wavelengths different but it hadn't made any difference then - 5ghz refused to accept validity of password.

So will keep you posted.

Makes the decision to download latest seed version even harder as I haven't yet got a clone in place...

Just in case you get bored Hex:

Topics for the OS X Yosemite Troubleshooting Exam (9L0-066)

Learn what topics are on the OS X Yosemite Troubleshooting Exam (9L0-066).

9L0-066 Basics
The exam is open resource. This means you may use resources such as Apple Service Articles, AppleCare Service Training in ATLAS, and the Apple public support site to answer the questions and pass the exam.

GSX access is recommended but not required in order to pass this exam. Test takers will need to use Apple public support articles listed in the Learning Resources sections of the training courses in ATLAS to answer some of the exam items.

This exam has 65 scored items and you have two hours to complete it. A passing score is 80%.

Exam Topics
Family Sharing (2 items)

• Using supplied scenarios, describe how to evaluate and isolate issues with iTunes devices.

Peripherals (5 items)

• Describe how to evaluate and isolate connectivity issues with peripherals on Apple products.

Accounts and Permissions (5 items)

• Describe how to evaluate and isolate permissions issues in OS X Yosemite.

Time Machine (5 items)

• Describe the functions and benefits of Time Machine.
• Based on supplied service scenarios, identify the troubleshooting procedures recommended by Apple.

Security and Privacy (5 items)

• Describe how to evaluate and isolate security and data privacy issues with OS X-based systems.

Startup Process (5 items)

• Describe how to evaluate and isolate OS X startup issues to determine the correct resolution to those types of issues.

File System (5 items)

• Describe how to evaluate and isolate file system issues.

Spotlight (1 item)

• Describe how to evaluate and isolate Spotlight issues.

Installation (5 items)

• Describe how to evaluate and isolate installation issues.

Recovery (4 items)

• Describe how to use Apple procedures and utilities to successfully recover an installation of OS X on a system.

Apps (5 items)

• Describe how to evaluate and isolate app issues with OS X-based systems.

Troubleshooting Tools and Techniques (6 items)

• Describe how to apply systematic troubleshooting methodology to correctly evaluate and isolate a given issue with an OS X-based system to determine the correct resolution to the issue.

Networking (5 items)

• Describe how to evaluate and isolate network and wireless connectivity issues with OS X-based systems to determine the correct resolution to those types of issues.
• Describe how to configure and set-up a wireless network using an Apple wireless product so that client devices can successfully access services on that network.

iCloud (5 items)

• Describe how to evaluate and isolate connectivity issues with iCloud-supported devices to determine the correct resolution to those types of issues.

Continuity (2 items)

• Describe how to evaluate and isolate connectivity issues with iCloud-supported devices to determine the correct resolution to those types of issues.

Last Modified: Nov 20, 2014

Been there, done all of that, experienced all of the same. BT HH was the only place I experienced WiFi issues - constant dropouts.

So I replaced the HH with a Linksys 8817 modem and Airport extreme. Wifi issue persisted.

I am the only equipment on the network - no nearby WiFi

Apple found no fault with my Laptop WiFi card (in the store)

Apple installed new WiFi card and ribbon cable

WiFi has worked seemlessly since - now 4 weeks.

I had tried everything suggested on the forum and more, and was a part of the seed programme.

Your situation may differ

I have no idea what a BT Homehub is, I use an Apple Time Machine router. All I know is that as soon as I upgraded to Yosemite on my iMac, WiFi turns off constantly. There is no fault in my router or anything else since other Macs and iDevices all work fine.

Yosemite is garbage. As I've said before, ever since Steve Jobs got ill (Lion came out when he was alive but no longer overseeing quality control) Apple has gone down the tubes and become what Microsoft always was, and is no longer deserves the accolades I once used to give. You are seeing how much influence Jobs had on the products since they now release crap.

I apologize to the hundreds (if not more) I helped convert to Apple over the years. They are now just another computer company.

"It just works" is now a sad joke.

Very interesting. If I get to 4 weeks without problems I'll let you know!

Very informative, thanks

http://meandmymac.net/2014/06/5ghz-wifi-networking-revisited/

I have bought Wifi Checker and run it.  Interesting.  The channels i was on earlier appeared less crowded so reverted and connections remained good BUT of interest to me was my contribution to the public  BT wifi fon network (which BT customers can sign up to offer a share of their bandwidth?) is kicking out a stronger signal - just- than my own network?!

If anybody understands BT / wifi fon signal / bandwidth sharing please get in touch

Sorry - slightly off topic. 

1st of all, there seems to be a small misunderstanding here about the abbreviation "BT". To the rest of the world that reads as "Blue Tooth", whereas to subjects of her majesty the queen, this will be understood as "British Telecom", same as in GCHQ, I suppose?

Ok, seriously now. Very glad my link has been useful. Furthermore: not only in GB do Fon networks invariably have an extremely strong signal. If you do not plan to use Fon, ever, have it switched off on your router.

Probably you are aware of this, but Fon is turning your personal BT router into a public hotspot and may well create static on your home network.

Now that we are entirely offtopic anyhow: turn off that "smart wireless" on your BT router. http://bt.custhelp.com/app/answers/detail/a_id/14094/~/how-do-i-change-the-wirel ess-channel-on-my-bt-home-hub%3F

And turning off BT Fon does not seem too obvious:

https://community.bt.com/t5/Apps-and-Extras-from-BT/BT-Home-Hub-5-and-FON/td-p/1 086830

Maybe get an ADSL modem without WiFi, and an Airport express (to handle NAT and WiFi) or so as your new setup. I wouldn't trust those BT boxes, they are proven to have built-in backdoors anyhow. http://www.csoonline.com/article/2134231/network-security/report-accuses-bt-of-s upplying-backdoors-for-gchq-and-nsa.html

Thanks for mentioning Fon! Maybe there is a clash between Yosemite's Discoveryd and Fon capable routers, who knows. They do run a customised version of OpenWrt firmware. Right, back to research...

http://en.wikipedia.org/wiki/FON

UPDATE FIX:

I can report that the replacement of the wi-fi card on warranty solved my wi-fi issue in my MacBookAir 13" running 10.10.1.

As this issue is really complex and may have many different causes, my fix may not work for you - so my issue was specifically:

On a fresh restart the wi-fi would connect but would completely disconnect in the first 5-10 minutes, or the 1st hour, and always disconnect straight after the computer would be woken from sleep.

The wi-fi icon in the menubar would say it was connected, but when clicking on it no wi-fi hotspots were listed.

Going to the system preferences the wi-fi would say it was off, clicking it on did nothing - only a restart would get it on again.

None of the workarounds listed here solved the issue (I tried everything).

I went to the Apple Store and was given reinstall advice (which didn't work of course), in the end the 90 day support line called it in for a hardware replacement - they replaced the wi-fi card.

If you have the exact same problem as above, a wi-fi card replacement may solve you problem.

JTFCD did your Macbook Air have any troubles with WiFi under Mavericks?

Are you suggesting some Apple hardware is not compatible with Yosemite?

Until an administrator branches us to a new topic...

Thanks Hex

I just posted this on the BT Users forum

"Sorry to awaken this topic from the dead....

I am using HH5a, opted in to FON, and Os10.10 MacBookPro

I have no problem whatsoever connecting and staying connected to 2.4ghz

I struggle since OS10.10 to either connect or stay connected to 5ghz

A persistent issue with trying to connect to 5ghz is the response "invalid password"  Only occasionally in the past 3 months has this not been a problem

the app WifiExplorer shows today that the only other networks on the same channels as my networks are the FON wifiX - both of which I presume are using my router/wifi as when I manually change channels these move with me.

Signal strength on 2.4  ghz is between 77 - 85, 5ghz 80+/- 1

Noise and signal noise ratio a lot higher on 2.4 than 5

(There is lots more info on wifi explorer but I dont know its relevance/meaning)

I have tried using manual channel selection and Smart Wireless and can't see much difference in 5ghz connection

Given a choice I would prefer to stay in FON but if there is overwhleming evidence that these hot spot networks are affecting mine, I would consider opting out.  Views/ guidance please.  Thanks.  And a Happy New Year too."

IS ANYBODY ELSE using BT Home Hub5a having this same issue?  I BELIEVE it has largely if only been since upgrading to 10.10.1 but can't swear to it.

IS IT SIGNIFICANT THAT SOMETIMES THE PASSWORD TO 5GHZ network is accepted and other times not?

What is it in OS10.10 that accepts/rejects a password?

The MacBook Air in question was a refurbished model bought late December last year - it never worked, fresh out of the box.

I do have another MacBookAir 11", and iMac 21" all running Yosemite and with no problems at all, so I assume that it's a combination of that model of MBA, along with Yosemite that was solved with a new card.

Whether it's a specific wireless card model that's at fault, I can't say, but if you have my specific issue, and a new wireless card is an option for you, it may work.