Windows 10/11 often blocks unsigned or older drivers needed for older VAG Tacho cables.
If the software detects the interface but gets stuck on "M-Flash" or asks to update firmware repeatedly, your interface firmware is likely incompatible with the software version. vag tacho interface not found full
[Vehicle OBD Port] ──> [VAG Tacho Interface] ──> [USB Port (Windows assigns COM 8+)] │ Must manually reassign to lower port ▼ [VAG Tacho Software looks at COM 1-4] How to Force a Lower COM Port Windows 10/11 often blocks unsigned or older drivers