I have been getting exactly the same problem on my Oct-2011 macbook pro. OSX Lion 10.7.3.
I have been searching various websites for solutions. There are various stories about upgrades, reboots, drivers, OS versions. Everytime someone says one of them works 5 others reply, "It didn't for me".
The most frequent and plausible explanation seemed to be the macbook pro aluminium frame blocked radio signals. Mine works perfectly if i'm in the same rooom or the next room to the router. But elsewhere I've got a 50/50 shot that it will connect or be fast enough to browse the web. My old Dell had a good connection every single time from anywhere in the house.
I eventually decided to bypass the problem by installing a usb wifi dongle. I went to my apple supplier. Peats of Parnell St. Dublin. They recommended edimax ew-7622UMn. I just plugged it in and to see what would happen, which was nothing.
I loaded the mac driver from the cd. rebooted, plugged it in again; still nothing... It couldn't even tell if there was something attached.
I downloaded the latest mac driver from the edimax website; still nothing.
So I decided to-****-with-it. I brought them both back to where I got them. They could do no better. The USB dongle wroked perfectly in every PC in the store and saw their wifi network. my Macbook pro and every apple machine they had couldn't even see the thing. Then they tried another MAC compatible wifi dongle; they got the same results on my machine and others.They suggested I call Edimax support.
Edimax said it should work fine and that they never saw this problem before!!!
The reason I bought a macbook is because I don't have time for this stuff. I just wanted a machine that works. That's exactly what it does 50% of the time. The other 50% I get a slow or no wifi connection
If you or anyone figures out how to make USB wifi work with a MacBookPro please post the answer. I just want reliable wifi from my Home office.
But there is no apple store in Ireland. Just resellers like Peats where I bought it. I already brought it back to them. They offered to give me my money back for the USB dongle, but that was it. I will probably go back to them to give it another go. Unless someone else has the answer. My problem seemed to be common to all the macbooks in their shop. Someone in the world must have added a wifi usb dongle to a macbook succesfully!
I'm having the same problem with my mid-2010 MacBook Pro. It was fine under Snow Leopard but it's been getting progressively worse under Lion.
CompuB is the best that Ireland can do for an Apple Store. There are a few branches around. I rang up the one is Swords to ask if they sell a USB wireless adapter and they said they don't do network gear. They asked why I wanted it and I told them. They said they had never heard of any wi-fi problems on MacBook Pro/Lon and when I told them to search for MacBook Pro wifi in Google, they just said don't trust the internet! They also said to call in and they'd run a diagnostic. So, I drove down to Swords (I live near Duleek) and, when I got there, they said their network was down and they couldn't run the diagnostic! Did I want to leave it in? No, I want to use it!!!
Works fine on ethernet and I'm writing this in Starbucks (Blanch) where AirPort is also fine.
I'm in Blanch because I just bought what you got – an Edimax EW-7622UMn – and I'm trying to configure it with Starbucks' free wifi. I can see it on System Preferences > Network as RTL81925S WLAN Adapter but I'm not sure if it's working. I'm not sure if you have to have "Wi-Fi" switched on for it to work or whether that only applies to AirPort.
I bought a MacBook because I was just so fed up with Wintel. It seems I have jumped out of the frying pan into the fire. Maye it's not only Microsoft that doesn't bother testing anything anymore. I expected more from Apple. I guess that everyone's far more interested in grotesque profits at the expense of customer service and working products these days.
FYI, bought a RealTek unit, which included one of those tiny CDs that won't load and gets stuck in the drive, causing a royal headache, but upon downloading the RealTek drivers and utility, which automatically opened on restart, it saw all of my networks under the "Available Network" tab, connected quickly and easily, and it happily wifi'ing away. As for "why don't you have Apple fix the AirPort card," I'll tell you why. I replaced the HD in this 2009 MacBook Pro with an SSD which worked beautifully and sped up the ancient unit to a point of usability. After doing this, the AirPort card gave me the dreaded "Wifi no hardware installed" error. I double checked the connections and all were good. The only connection I couldn't check was the antenna that goes up the inside of the screen. So I brought it to the Apple Store where I was scowled at and they told me Apple refuses to fix anything once you open the machine due to "Liability reasons." I told them I'd sign a liability waiver. Still no go. So my choice was to send it to a third party repair center, or pay $11 for an external radio. Guess which one I picked?