Hi all, I have a late 2011 Macbook Pro 13, which is unable to join my wifi network despite detecting it with good signal strength. It reports the error "The wifi network (Name) could not be joined". It seems to join the wifi network alright when I start up and use the option key (so, outside of the OS, I suppose). I am using El Capitan. Can anyone advise on what the problem might be? Thanks in advance.