anyone's wifi not working properly?

Is it an Apple router? If not, is the firmware the latest?

How far is your iMac from the router? Do you have Media Access Control (MAC filtering) turned on? Is WPA2 encryption enabled?

Other devices in the same vicinity work ok?

Have you tried disabling all but the iMac's connection to the WiFi to see if it is a bandwidth sharing problem for the WiFi?

I've been experiencing similar connectivity issues within the past week. My PC and laptop are connected to the internet at normal speeds, and we are able to stream hi-def Netflix programs to my TV, but my Mac is unable to garner a download speed capable to stream 240p youtube videos. Prior to this week (late last week) the Mac was fine, hitting speeds equivalent to that of the laptop on wireless. I was reading Netgear support and they say that iOS6 has been having compatibility issues with their routers. I would assume this is the cause, although my iPod can stream Netflix without issue and it is fully updated to iOS 6.0.1. I ruled out wi-fi bandwith sharing issues as I am able to be online on xbox gaming while my better half watches Downton Abbey (Netflix) on the other TV. At this point I'm trying to figure out a way to roll back the latest software updates on the Mac to see if that has any effect, but signs point to that not being an option. Any additional suggestions would be welcome, although I'm unwilling to dig too deep into the router since all other connected devices are working fine. I think a software update to my Mac is going to be the fix but the wait could be annoying... Ok that's all.

I am having the same exact problem. I have an intel iMac running 10.6.8. I'm writing this from a friend's laptop running 10.6.2 that's working just fine off of the same wifi connection. the iMac was working fine, but gradually started disconnecting more and more frequently over the course of the last week or so. This evening it finally won't stay connected for more than 45 seconds to a minute. It will barely load google. Tried this: https://discussions.apple.com/thread/4687085?answerId=20917850022#20917850022 but it didn't work. Please help! Thanks!

The only way we might be able to fix this is if you try to isolate the iMac as the only device connected to the router and ensure it is connected via a WPA2 secure connection. Otherwise the bandwidth on the router might be causing problems. It may not be allocating all its bandwidth to the iMac and as a result drop its connection when it isn't certain which machine to allocate to.

There have been some users who have had troublesome wifi since LIon through to Mountain Lion. There doesn't seem to be a one fix solution.

I've seen reports on here where people have changed the wifi channel and it's resolved their problem but hasn't helped others. Might be worth a try.

There's also this oldish link that has helped some, although not everybody. It talks about Lion but still seems to be relevant to Mountain Lion. Also check out the links within the article:

http://osxdaily.com/2011/11/06/lion-wi-fi-problems-solution-mac/?utm_source=feed burner&utm_medium=feed&utm_campaign=Feed%3A+osxdaily+%28OS+X+Daily%29&utm_conten t=FaceBook

The fact you hardwired it and still had issues, says you have the wrong network settings. Try using http://www.opendns.org/ instead.