Airplay

I just bought a new Denon x1000 AV receiver that has a Airplay feature. Ive connected it to my old Mega 100wr router with an ethernet cable. Ive also downloaded the Denon remote app on to my iphone 5 and ipad 2(Both devices updated with iOS 7). The remote app works fine with the receiver on both devices, but somehow the airplay icon doesnt appear. Ive got it to appear for a while on both devices and then its streams music to the receiver perfectly. But once i stop using it, it dissapears. Ive unplugged my router trying to reset it a couple of times, which i think makes the icon appear on my devices, but it wouldnt stay there. Could my router be too old or is there a setting I should look at changing.