after update to 10.9.1. wifi dropouts

Have you tried switching channels on the 5 Ghz network and checking ?

I have the same problem and using the Airport Extreme. I can recover by turning off the wifi using the WIFI Icon at the top of the screen then turn the wifi back on again works fine for awhile with no real pattern that I can see.

Has anyone logged the issue with Apple support?

Yup. Same here. I can't explain it nor can I figure out a consistent set of circumstances that leads to the problem. But after a year-and-a-half of perfectly fine wi-fi performance, my 2012 rMBP is now frequently FUBAR on 10.9.1. Wifi appears to stay connected, but nothing will happen. I've tried turning wifi of/on like others have suggested. Sometimes it works. Sometimes it doesn't. Completely rebooting often seems to solve the issue, but isn't really practical when it goes down while I'm in the middle of doing something.

Try rebooting your wireless router. The problem with anything that fluctuates, like radio waves or technology in general, is that it changes. There may be people nearby who got new wireless routers for Christmas. Your ISP might have some bugs in the IPv6 implementation and is confusing Mavericks.

I was on the Apple support chat last night to discuss this problem and the wifi, router all checked out fine so they gave me a procedure to reset the SMC and to do a PRAM. All was well until just a few minutes ago when the wifi froze again. This happens at least once a day now so its a bit annoying.

As a note, this never happened on my 2006 IMac running Lion or anyother device on my wifi network so I am guessing its either the new IMac or the 10.9.1. The support seems very interested to help so I will go back with my findings and be sure to let you know what I find.

So I tried 10.9.1 again, and I'm not having the wi-fi packet drop problem anymore. Not sure what was going on before.

Same problem here. Switched to Maverick and experiencing wifi dropouts. Turning wifi off and on generally solves the problem but is annoying as connection last 2 minutes. Router is not the source of the problem as it keeps occuring with 3 different routers over a few days.

Time machine was off during update. Any tip to go back to earlier version of Mac os?

I've been dropout-free for a week or two now. I followed the advice I found here and elsewhere, removing the problem wifi connection and removing its keychain entries. That seemed to help, but then it didn't. The thing that really seemed to get things running right was switching my wireless router to run on channel 11. Since then, it's not been an issue.

It kind of makes sense. I work in an office, and they have wireless routers set up in the room. I've long had dropout issues with them -- and still do. But I don't control those routers. I do control the super-secret one hidden under my desk -- the one I changed to 11 -- and I'm now staying connected just fine.

Thanks to Apple Care folks, changing frequency fixed my problem on wifi drop outs. Apparently, one of my neighbor's added a new wifi router with the same same signal strength and channel so I am guessing that was source of my drop outs. My Apple Airport router was set to automatic but now set to an off channel not shared with anyone local.