How to configure a VLAN interface as 2nd WAN on RB750GL?

Hello,

I’m trying to setup a dual wan network on a RB750GL. RouterOS 6.13. The logical diagram is attached to this port.
I have followed the next steps:
Port 1 - independent master port, WAN01 directly connected and DHCP client; it receives IP address and internet is working!
Port 2 - master port for ports 3 and 4.
Port 5- not slave, independent, trunk with 2 VLANs assigned. Is directly connected to a trunk port on a D-Link managed L2 switch 802.1q with VID 80 and VID 20.

  • VID 80 for LAN purpose and bridged to port 2
  • VID20 - will bring the WAN02

What is working : using bridging I have ports 2-4 connected to VLAN 20 and the router is reacheable from the devices connected to the switch on access ports VID88.
LAN IP network 192.168.88.0/24, DHCP on the bridge.

What is not working: VLAN20 is setup as a DHCP client , but is not receiving IP addresses from trunked port 5 from the DHCP server which is connected to the L2 switch on an access port. ( I have a home router in the LAB, but it will be a public IP address , DHCP client).

VLAN 20 shoul receive IP address and be configured as WAN port, with NAT and firewall. Part of the LAN devices will reach the internet on WAN 1 and other part on WAN 2.

Where am I wrong?
my network setup with mikrotik RB750GL(6).png