Wifi issues with both iPhone and iPod

I have an iPod touch 4g and an iPhone 4. Both can not use the wifi for some reason. But everything else in my house can use the wifi. It is a dual Band Apple Airport base thing that is my wireless. My iPad, Macbook etc. Can still use the wifi. I have also reset the network connections and it will work for about 4 minutes then wont work anymore. So I need to restore?
iPhone 4 iOS 4 iMac i5 Quadcore 8gb ram 1T hard drive iPad 16 gb wifi model