Cheers kevin, filed 2 bugs documentation: FB23530504 the header/doc inconsistency: kFeatureHardwareVlan is referenced in the getVlanTag()/setVlanTag() doc comments in IOUserNetworkPacket.iig but defined nowhere in the public SDK (exhaustive grep: 4 hits, all doc comments). suggestion: FB23562845, the enhancement request for a public hardware VLAN capability, with the usecase detail you asked for included. I also ran the experiment you suggested, declaring IF_HWASSIST_VLAN_TAGGING (0x00010000) via getFeatureFlags() on macOS 26.3.1, with live tagged traffic on a vlan(4) interface over the driver: Alongside kIOUserNetworkHWAssistSoftwareVlan: no behavioral change. getVlanTag() never returns true; tags remain inline in both directions. Alone: also ignored and the vlan(4) child clamps to MTU 1496, i.e. the unpublished bit doesn't even receive the VLAN-MTU accounting the published bit provides. It's discarded wholesale, not partially honoured. One refinement to I think you'll find that we strip the value: in our te
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App & System Services
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Drivers
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