My Airplay speaker drops out after a minute or two of palying - why?

I have a Wren Airplay speaker and it continues to drop off my network. I have tried a Asus N66 and an Airport Express - same results. I have a different name for the 5GHz and 2.4 GHz network, WPA2-AES security, and I am only 10-20 feet from the router. I have checked my setting and they match the recommended setting from Apple. Any ideas?