USG 3 WAN trunk VLANs forwarded to LAN

#1

Is there a way to configure the usg to pass the normal internet vlan of 1 and the IPTV vlan 3999 through WAN to LAN of the USG and then to a SWITCH which has the ability to edit vlan traffic?

#2

I have never done it,but someone has a config here that might help.