The present invention provides compounds, pharmaceutically acceptable compositions thereof, and methods of using the same. The process involves establishing a PPP2 link with the IWF in response to detecting a mobile IP data session request from the UT, detecting a PPP1 link with the UT in response to the PPP2 link being established, detecting that a PPP2 link failure has occurred, and reconfiguring at least one of the WCD and the UT to an initial state. Thus, it is possible to disperse a shock wave generated from the intrados at the trailing edge to prevent the generation of a strong shock wave, thereby reducing the pressure loss caused by the shock wave. Moreover, the plug-in connectors are provided with an essentially cylindrical outer sleeve respectively.