N-Tron 708M12 - Manual (Page 58)

(Revised 2011-07-20) Page 58 of 156
VLAN – Configuration
Replace VID Tag with Default Port VID
Specifies whether or not to replace the incoming VID tag with the port's designated VID.
Perform Ingress Filtering
Specifies whether or not to filter out ingress frames when a VID violation is detected.
Discard Non-Tagged for Ports
Specifies whether or not non-tagged ingress frames are dropped by the selected ports.
Note that for convenience in most frequent use:

Ports are deleted from group1 as each port is added to another group.

Ports are added to group1 if a deletion leaves a port with no group.

If it is desired to have a port on group1 and also on other group(s) configure group1 last to achieve that.