Multi WAN routing won't work properly (randomly)

[huamiao]

I have 2 PPPoE WANs from same ISP, so they have very similar IPs (like 1.1.1.x) and same gateway.
I create a failover WAN group:
WAN0 - Tier 1
WAN1 - Tier 2
And point LAN's gateway to this wan group.

My problem is the internet sometimes can't be accessed after a reboot and all gateways (SYSTEM->Gateways->Single, monitor are enabled) are online. WAN Groups shows all gateway's online. In this situation, if you:
1. Disconnect a WAN(WAN0 or WAN1) -> Internet OK
2. Disconnect all WANs and connect WAN0 first and then WAN1 -> Internet OK
3. Disconnect all WANs and connect WAN1 first and then WAN0 -> Internet Failed
4. Goto firewall, set policy routing to WAN0 -> Internet Failed
5. Goto firewall, set policy routing to WAN1 -> Internet OK
6. ALL WAN interface works properly if you try to access internet from the firewall itself (use curl and specify wan0 or wan1)

Have no idea how to solve this issue, can anyone help me on this? Thank you very much.

[huamiao]

seems like as same as this post https://forum.opnsense.org/index.php?topic=34189.0