I've been following this thread since I installed Yosemite. Maybe I have not read all the 80 pages, but probably most of them. Yes, of course, I'm experiencing the dropping connection issue and tried, with no success, many of the potential fixes suggested above. I also got frustrated updating to 10.10.1.
Reading one of the recent posts where someone wrote about the 2.4Ghz bluetooth/wi-fi interferences, something reminded me of a connection issue I have faced when my iMac 27" late 2012 was just left the box. By that time, I think we were at Snow Leopard age, my internet speed was slow as **** and causing performance loss even on offline tasks. Still by that time, the solution I have found was simple for such a mysterious problem cause: to change the router's frequency channel. So simple that I never wanted to understand what caused that problem.
I know it's a common sense that our problem is being caused by software (Yosemite) and not hardware because everybody's setup was working perfectly with Mountain Lion, but I know people who installed Yosemite in 2-or-3-years-old macs (sorted models) and are happy with their new system which keeps connected and stable over wi-fi. We're a group of people with the same problem but perhaps we have different causes.
Perhaps not.
Every try is a hope and so I tried to change my frequency just because I remembered that it once easily fixed a big problem.
It was set in channel 4 (just because sometimes I make some experiments randomly changing my router's channel to see if I get a better signal for a SmartTV which is distant from the router) and I set it back to "auto". Since that, I have already experienced 6 hours of stable wi-fi connection.
It's too early to say if it has definitely fixed my problem, but if you've been clicking on your wi-fi network every 3 minutes to reconnect, would you please waste a little more of your finger muscles and visit your router's firmware page to check your channel settings? I can't wait to make part of a group of people who have fixed this with the same solution.
This is my first post ever at this forum and I hope it helps one or two. Or three. 🙂