This is the inRange property of the same ether:NiErrStats tracker: a cumulative Unsigned64 count of frames that were a legal Ethernet length but still registered as errored, i.e. symbol or alignment errors rather than a size problem. On this specific interface it points at a physical-layer defect (marginal cable, dirty or failing optic) rather than an MTU or software issue, since length-correct frames shouldn't normally error out. For example, this counter climbing from 0 to 1,842 over a week on one adapter's Ethernet interface while its sibling interfaces on the same blade stay at 0 singles out that one link's cabling or transceiver as the culprit.