The SM-G920T (Exynos 7420) uses a Shannon 333 modem. Most NV repair guides assume a Qualcomm chip. Do not attempt QPST on this model — you will not even get a COM port.
This is for experts only. Using (Qualcomm Product Support Tool) requires converting your Samsung’s Exynos modem to a diagnostic port — which is not always supported on the G920T (since it uses Shannon modem, not Qualcomm). In fact, QPST does not work with the SM-G920T because the modem is not Qualcomm-based. sm-g920t nv data file