Andy, see here /g/nanovna-users/files/Dislord%27s%20Nanovna%20-H%20Firmware last fw version from DiSLord 1.0.69. Attention! ZIP file has FW for all variants of NanoVNA: NanoVNA-H NanoVNA-H4 and for NanoVNA V2/V2Plus/V2Plus, but this FW works not with newest HW of V2Plus/V2Plus4