Iphone 3GS-AOL Email from Iphone No Longer Working

Hi Everyone,
Im a bit confused. The last couple of weeks I have had major issues trying to receive my AOL email from my iphone. It has worked perfectly without issues for one year and then suddenly I have been receiving messages such as password incorrect or user name/password for imap.aol.com incorrect.
Ive been trying to read alot of threads about this all over the internet and tried to set up my AOL account manually and I still get the error messages.
The weird thing is when I go home from work and get my Iphone onto my wireless network ,all of a sudden the emails work perfectly again.
Is there someone out there that can help me? Im really lost as to what to do..
3GS 16GB iOS 4.3.1 iOS 4