The version of the firmware I currently have (18.104.22.168) is retro when it comes to VLAN trunking.
When the Port Mode is in "Trunk", you can only have tagged VLANs pass through the port. When the Port Mode is in "Access", you can only have a single VLAN pass through the port, untagged.
Most switches today like to have one VLAN that is untagged for each port (usually called the PVID, or priority VID, which is the VLAN that the switch associates with untagged packets passing through the port).
If you want to configue the switch like this, you have to put the Port Mode to General
, and then Frame Type to Admit All
. You can then set the PVID (which is ignored) and then set one VLAN as untagged and further VLANs as tagged.