If a port is a member of only one VLAN, select Untag from the Port column. The
VLAN with Untag selected can connect to the port, but other VLANs cannot access that port. Select — for all the other VLAN rows in that Port column.
If a port is a trunk (span) port, it connects multiple VLANs to an external device,
such as a switch, which also supports trunking. A trunk port must have tagging (IEEE 802.1Q) enabled for all VLANs that connect to that external device. Select Tagged at all VLAN rows that need to be trunked, and select Untag at one or more VLAN rows in the trunk port column that do not need to be trunked, for example, the default VLAN. Each Ethernet port must be attached to at least one untagged VLAN.