Enable Developers option for USB debugging:
Go to Settings ->More->About Device and tap on the build number 3-5 times. It will notify that developer option is enabled.
Go back to Developers options and settings and Select USB debugging
Enables Modem Option on the Samsung Galaxy S5/S4:
Go to Samsung Galaxy S5/S4 dialer and dial *#0808#. The USB Settings will opened.
Go to AP USB settings select the "RNDIS + DM + MODEM" and Click OK.
Connect the Samsung Galaxy S4/S5 to laptop and check the device manager. There must be a com port appear for your laptop. make note of the comm port and use it QPST and QXDM.
