Oh by the way, everything works fine, but can't connect to the internet, here is what the network diagnostics says:
Wi-Fi is connected, green light,
Wi-fi settings is connect, green light,
Network settings is connect, green light,
ISP is connected, green light
Internet Failed, red light
Server Failed, red light
The exclamation mark is gone, but what gives??! I can connect to the ISP but not the internet? All my other devices works just fine
I had this exact issue and spent hours on the phone with apple as well as my internet provider trying to solve the issue. As far as I know, there is no solution for the issue yet but I temporarily dealt with it the issue by reinstalling OSX Lion, and not updating to 10.7.2! I am currently just running 10.7 and my internet is back to normal. Hope it helps.
I've just tried every fix I could find on the internet, talked through all the suggestions from AppleCare on the phone, reset my router and changed the channel, all with no joy.
I then connected my Macbook to the internet via Ethernet and had connection. I removed the ethernet cable, and now the Wi-Fi is working!
No idea how or why this worked but it seems to have. I was having problems with a self-assigned IP address and this now seems to be resolved.
I have the exact same problem! My imac, operating with 10.7.2 will not connect and has the ! over wifi icon. (sadly connecting the ethernet cable and disconnecting again didn't work for me).
My MacBook is running with os 10.6.8 and works with the router although now I can't update the operating system or I'll have the same probs with Macbook!
So, I've spent most of this week back and forth with apple support, TP-Link and ISP. (all firmware for router completely updated) and nothing's worked.
I have been told by an apple senior technician that the TP-LINK router is not compatible with computers operating with os10.7.2 and I need a different router.
Just thought I should let everyone know to save you wasting loads of money on phone calls like I just did!
At some hotels' wi-fi or on intercity buses, all smartphones of any trade connect smoothly but My Mac did not.
I got this from :
The issue seems to be the set up of the router, which is filtering MAC address. Manufacturers of router usually deliver the router to customers like Megabus or other public wifi spots with the feature turned "off". The technician in charge of the router at the Megabus refused to help, he stated that his son's Mac connects without problems. Of course, he would not be motivated to turn the router filter on just for some travelers ...