Draytek Vigor 2925 Series User Manual page 175

Subnet
Permit untagged device in
P1 to access router
Note: Leave one VLAN untagged at least to prevent from not connecting to Vigor router
due to unexpected error.
To add or remove a VLAN, please refer to the following example.
1. If, VLAN 0 is consisted of hosts linked to P1 and P2 and VLAN 1 is consisted of hosts
linked to P3 and P4. VLAN0 and VLAN1 are configured with different subnets.
Choose one of them to make the selected VLAN mapping
to the specified subnet only. For example, LAN1 is
specified for VLAN0. It means that PCs grouped under
VLAN0 can get the IP address(es) that specified by the
subnet.
It can help users to communicate with the router still even
though configuring wrong VLAN tag setting. For Vigor
router has one LAN physical port only, it is recommended
to enable the management port (LAN 1) to ensure the data
transmission is unimpeded.
163 Vigor2925 Series User's Guide