Dell PowerEdge FN I/O Module Configuration Guide 9.10(0.0)

For VLAN classification, these packets are treated as untagged. However, the dot1p value is still honored when you configure service-class dynamic dot1p or trust dot1p.

When priority-tagged frames ingress an untagged port or hybrid port, the frames are classified to the default VLAN of the port and to a queue according to their dot1p priority if you configure service-class dynamic dotp or trust dot1p. When priority-tagged frames ingress a tagged port, the frames are dropped because, for a tagged port, the default VLAN is 0.

Dell Networking OS Behavior: Hybrid ports can receive untagged, tagged, and priority tagged frames. The rate metering calculation might be inaccurate for untagged ports because an internal assumption is made that all frames are treated as tagged. Internally, the ASIC adds a 4-bytes tag to received untagged frames. Though these 4-bytes are not part of the untagged frame received on the wire, they are included in the rate metering calculation resulting in metering inaccuracy.