[OpenWrt Wiki] VLAN
https://openwrt.org/docs/guide-user/network/vlan/switch_configuration05.11.2021 · A very common default VLAN configuration on many off-the-shelf routers is the LAN↔WAN separation. OpenWrt default configuration on such devices does usually mirror the stock configuration. Most of such routers only contain a single network interface (eth0), leading to a 5-port VLAN-enabled switch that is virtually partitioned into a LAN and WAN network by …