Airplay audio cuts out intermittently with iPad

Everytime I play anything via airplay with my iPad through the Airport express, it just play fine for 2 minutes and then the audio cuts out for 6-10 seconds. Then the audio comes back again, but it will cut out repeatedly few minutes. The Express units are both connected to Extreme via wireless. After rebooted all devices and updated firmware, nothing works.The Express to Extreme connection is