Question to topic configuration of vlans on gl-ar 750

Hello,

I got a test running to get the definition how to configure a vlan on the switch of gl-ar750.

specs:
gl-ar750, 2.272
wan and lan1 connected to 100 M/bit LAN on a managed switch. managed switch with vlan 3 (LAN) and 4 (WAN) on the corresponding ports to the gl-ar750.
gl-ar750 WAN = eth0.4 → 192.168.179.3 (towards dsl router)
gl-ar750 LAN1 = eth1.3 → 192.168.8.1 (towards lan devices)

configuration 1:

config switch_vlan
option device ‘switch0’
option vlan ‘1’
option vid ‘1’
option ports ‘0t 1t 2t’

config switch_vlan
option device ‘switch0’
option vlan ‘2’
option vid ‘3’
option ports ‘0t 2t’

config switch_vlan
option device ‘switch0’
option vlan ‘3’
option vid ‘4’
option ports ‘0t’

=> result: lan device 192.168.8.2 pings 192.168.8.1 correctly!

configuration 2:

config switch_vlan
option device ‘switch0’
option vlan ‘1’
option vid ‘1’
option ports ‘0t 1t 2t’

config switch_vlan
option device ‘switch0’
option vlan ‘2’
option vid ‘3’
option ports ‘2t’

config switch_vlan
option device ‘switch0’
option vlan ‘3’
option vid ‘4’
option ports ‘0t’

=> result: lan device 192.168.8.2 cannot ping 192.168.8.1!

Please help me in understanding, why port 0 has to be in tagged mode for vlan3, so that lan device 192.168.8.2 can ping 192.168.8.1 (LAN1 of GL-AR750)?

Regards
Mikee