Homesharing not working between iOS devices and iMac

My homesharing is not working between my iMac on one side and my iPhone and iPad on the other side. However, the my MacBook Air connects perfectly and have never made any problems. It is not that I don’t know how to turn homesharing on and the first time I did it on my iPad it actually mapped the files on the iMac however it could only play a few of them. I got the message “requested Url is not..”. Restarting everything solved nothing and it doesn’t even map the files anymore. Now I have opened UPD and TCP ports but nothing helps. What to do?
(iMac, OS X 10.5.8)
(Iphone, iOS 4.3.5)
(iPad iOS 5.01)
(Router, Ausu RT-N56U)

How to set up iTunes Home Sharing to stream to your iOS device

If you are jailbroken, cant help ya.