Occasionally, a new firmware introduces bugs (e.g., Wi-Fi dongles stop working, or the web interface becomes slow). Hikvision locks downgrades to prevent security rollbacks.
Hikvision’s EU or US download portals often archive legacy firmware. You need to navigate to Service & Support > Download Center > Legacy Products > DVR > Turbo HD > DS-7104HGHI-SH (Yes, sometimes they recategorize it under SH). hikvision ds-7104hghi-k1 firmware download