This counter tracks the number of invalid RNG-REQ, or ranging request, messages the headend has received on this interface. Admins use this to detect a broader interface-level problem with ranging requests, as opposed to counters scoped to a single SU, which could indicate protocol-level noise or an RF issue affecting many devices at once. For example, a sudden interface-wide spike in cwdIfHeStatusInvalidRangeReqs, rather than an increase isolated to one SU, would point an admin toward a shared-interface cause like interference rather than one bad device.