Question: can vlan 1 be tagged?
Answer: Untagged VLANs A switchport may be a 'tagged' or 'untagged' port. ... The switch port is configured with a VLAN ID that it will put into the tag. Most switch ports will use this mode by default, with VLAN ID 1. When a frame leaves an untagged port, the switch strips the VLAN tag from the frame.