Have you tried Chrony instead of Ntpd ?

    System time     : 0.000084656 seconds slow of NTP time
    Last offset     : -0.000029673 seconds
    RMS offset      : 0.000046217 seconds
    Frequency       : 17.760 ppm slow
    Residual freq   : -0.001 ppm
    Skew            : 0.012 ppm
    Root delay      : 0.001419884 seconds
    Root dispersion : 0.000967303 seconds