Methods, devices, and instructions stored in non-transitory computer-readable medium are provided for adaptively adjusting when a mobile device requests fast dormancy (FD) by determining when applications executing on the mobile device stop using a connection to a cellular telecommunications network. An adaptive fast dormancy controller function executing on a processor of the mobile device monitors network traffic activity by the applications. The adaptive fast dormancy controller function may determine that an open network connection should be released using a device traffic inactivity timer that times durations of network inactivity by applications. The duration of the device traffic inactivity timer may be adjusted based upon observed application and/or network conditions. Multiple device traffic inactivity timers may be used to enable timing traffic inactivity of each application or groups of applications executing on the mobile device.