Multi wan load balancing at same tier issue

[erickufrin]

I am having a weird problem with multi wan which I cannot figure out the solution. I have gone to the extent of a wipe and reload of my fw software and starting the config 1-by-1 only to still have the problem. Now asking for help.

When I put the LAN fw rule for outbound traffic into load balance group where both WANs are in same Tier1 - I experience intermittent traffic failures.

I have multi wan setup per the guide.

WAN1 = cable modem w/ dhcp public IP
WAN2 = opnsense is NAT IP behind DSL "router" which has public IP

After several days I finally made some discovery after looking into the WAN2 DSL router logs - it is denying traffic for reason of packets "invalid src IP address" of WAN1.

Traffic shouldnt be coming in an interface that did not originate from, correct...??

When I have either WAN configured as Tier1 and the other as Tier2, I have zero issues like this.

Only when they are both at the same Tier does it occur. Please help

[erickufrin]

I found a workaround...on the DSL router there is a "supplemental network" option to add IP's behind the DSL router... Adding WAN1 to that seems work.

Traffic is flowing now with my work around. Still seems strange that packets were leaving WAN2 interface with WAN1 source IP.