Just want to throw in my 2c, as I had really hoped that there would be a fix, or at least an acknowledgement of the issues by now. I had similar issues to those shared here when I tried to upgrade my (1 month old) Laptop to Yosemite. It not only crashed WiFi for that new computer, but also for my iMac, iPad and iPhone. I reverted back to Mavericks, and after a little messing around, everything is stable again, which I guess is a fix of sorts.
However, in the hope that someone in Apple monitors this thread, I want to give a little feedback.
1. I greatly appreciate all of the suggestions, altruism and help offered by individuals on this thread, so thank you. However, that should at most be triage for a short period of time while Apple fixes the problem. Apple owns the issue, not its loyal user base. It is now coming up on 2 months since this issue first popped. I am a very long time Apple user, and a big part of the reason I am is because I am happy to pay a significant premium for an intuitive, no fuss operating system and reliable product. I have neither the aptitude or desire to spend hours trying out different ways to paper over the cracks in a premium product. When you buy a Rolls Royce, you don't expect to have to climb under the car and tinker with the engine every morning to get it to start, even if it has British electronics.
2. Apple, you risk killing your Xmas/year end business. I don't want to, but I am close to being forced to buy a PC Desktop. Like many small businesses, I have to make certain purchases before the end of the year, and the clock is ticking very loudly. I cannot afford to buy a new iMac with a Yosemite OS that is not going to work, and worse still, potentially kill my entire network. I realize that I am just one person, but I suspect I am not alone, and at the time of year when people are buying Xmas presents, or making year end transactions, Apple really needs to provide some reassurance, or at the very least acknowledge the problem.
3. A sort of thank you. I sold my Apple stock today. I've held it since the week Steve Jobs returned, and I have to say I greatly appreciate what the company has done to grow the stock (pun intended). It has certainly helped me to afford the premium price of Apple products over the years. I bought the stock because I believed in Apple, and because I saw both potential and magic when Jobs first came back. The debacle with Yosemite has been enough to persuade me personally that the magic has gone, or at least has become unstable. I hope I'm wrong, as in the future, as a consumer I still want the quality of products Apple has provided over the years. However, now I'm just hoping for it, rather than putting my retirement behind it. Go on Apple, I dare you, make me regret selling, or better still, give me a reason to buy back in.