Hello, I have been using my rMBP for a year. Recently, there are some problems in using wifi in public areas. For example, in some stores, I have the password. I could use wifi in those stores in the past. However, recently I can't. By clicking on the wifi symbol on the top right, Mac OS indicates that it is connected to the router will strong signal level. However, when I don't click the wifi icon, I see an exclamation ! mark. So, is it connected or not? Know how to resolve the issue? I am using Mac OS/X 10.8.5. Thanks.