Okay, I was in the middle of writing that when my wifi went out, and I was going to have to reboot, so I just left it. I didn't know until now that it actually got posted!
I have a 2007 iMac Intel desktop that has all the problems with 10.10.1. I also have a MacBook Air 11" that had tons of problems with email. Once I thought all my emails were lost. So I did a rebuild (Mail/Mailbox/Rebuild), and it seemed to do something, then freeze. I shut down out of frustration, and when I rebooted hours later, all my emails were fine and the problem was ALMOST solved. During the time it was worst on both computers, it would never take my password. But after the email thing on the MB Air, if I rebooted it would usually give me wifi.
But not the iMac. That sometimes shows up full-strength wifi, then after 10 minutes or so, shows 3/4 strength, then will suddenly just flip out altogether. And the password never works (my husband's computer is on the same system, and he never upgraded to Yosemite. So I hesitate to change the password for fear his will also go out. He's very technically challenged, and I'm getting way out of it having been retired for several years now.)
Anyway, I came across this in this discussion from ShockoeStudios.com on Nov. 20:
UPDATE: Solved Wifi issue with MBA 2013... so far!
Hardware:
MBA 2013
Clearwire Clear Spot 4G Apollo
ISSUE: after Yosemite update (and 10.10.1 update) wifi connection continuously dropped and reconnected. No issues before Yosemite.
I was able to test using several wifi networks, which other than being a little slower than expected, all worked with no connecting issues.
Attempted fixes: All the standard ones found in this forum and other places (ie. delete network settings and preferences. Delete and recreate wifi network with new name... the list goes on.) Some very temporarily seemed to solve the issue... only to see it return after a few quick surfing sessions.
SOLVE: (at least for now... I'll update this every 24 hours for the next few days)
While in an in-depth conversation with high level Apple tech Scott... I learned that deleting the wifi preferences and settings files wasn't all the files related to wifi connection. Keychain holds the wifi passwords.
I then changed the settings in my modem to not require a password. It connected after asking me "this network previously was protected by a password. Are you sure you want to join it?" (or something along those lines) I agreed and was connected without any drop offs... Yah!!!
After a few hours of success, I changed it to WPA2 passworded (same question box popped up, I agreed)... connect with no issues... Yah again!!!
AFTER 24 HOURS: Still successfully connected!!!
NOTE: I believe this issue is caused by a corrupted keychain entry. Apples help forum shows other high level network techs have notice this issue too.
I'm assuming that just deleting the keychain related to this wifi connection would accomplish the same results. You would just need to re-enter the wifi password.
Watch for updates every 24 hours for the next few days... any feedback would be great. Let me know if this helped your issue.
Since my problem is with the password, this makes sense. I haven't seen whether it's still working for ShockoeStudios.com. I hope to try it on my desktop, because for now my MB Air seems to be working fine.