Lan Port 1 --> VLAN 1;
Lan Port 2 --> VLAN 2;
Lan Port 3 --> VLAN 3;
Lan Port 4 --> VLAN 3;
Wireless --> VLAN 4;

config interface 'loopback'
    option ifname 'lo'
    option proto 'static'
    option ipaddr '127.0.0.1'
    option netmask '255.0.0.0'

config globals 'globals'
    option ula_prefix 'fd61:03fe:3974::/48'

config interface 'lan'
    option ifname 'eth1'
    option force_link '1'
    option type 'bridge'
    option proto 'static'
    option ipaddr '192.168.1.1'
    option netmask '255.255.255.0'
    option ip6assign '60'

config interface 'wan'
    option ifname 'eth0'
    option proto 'dhcp'

root@OpenWrt:~# swconfig list
Found: switch0 - 10.mvsw61xx

config switch
    option name 'switch0'
    option reset '1'
    option enable_vlan '1'

#wan port
config switch_vlan
    option device 'switch0'
    option vlan '1'
    option vid '100'
    option ports '4 5t'

#port 1
config switch_vlan
    option device 'switch0'
    option vlan '2'
    option vid '2'
    option ports '3 6t'

#port 2
config switch_vlan
    option device 'switch0'
    option vlan '3'
    option vid '3'
    option ports '2 6t'

#port 3
config switch_vlan
    option device 'switch0'
    option vlan '4'
    option vid '4'
    option ports '1 6t'

#port 4
config switch_vlan
    option device 'switch0'
    option vlan '5'
    option vid '5'
    option ports '0 6t'

config interface 'loopback'
    option ifname 'lo'
    option proto 'static'
    option ipaddr '127.0.0.1'
    option netmask '255.0.0.0'

config globals 'globals'
    option ula_prefix ' ( ...whatever your prefix is... ) '

#Lan on switch port 1
config interface 'lan'
    option force_link '1'
    option proto 'static'
    option netmask '255.255.255.0'
    option ipaddr '192.168.0.1'
    option ifname 'eth1.2'

#Another local network on switch port 2
config interface 'someothernetwork'
    option proto 'static'
    option ifname 'eth1.3'
    option ipaddr '192.168.8.1'
    option netmask '255.255.255.0'

#WAN on the wan port
config interface 'wan'
    option ifname 'eth0.100'
    option proto 'dhcp'

#Wireless
config interface 'wi'
    option type 'bridge'
    option _orig_ifname 'wlan0 wlan1'
    option _orig_bridge 'true'
    option proto 'static'
    option ipaddr '192.168.6.1'
    option netmask '255.255.255.0'