Just wanted to give an update.
I upgraded my NVR to NVR_K74_BL_ML_STD_V3.4.100_180310
I manged to get Hik-Connect working on my iPhone and iPad (and the wife's iPhone) so now I have instant replay from alerts, with better images than the email images. I have iVMS-4200 3.5.0.7 Client running...