DDNS on WAN2

I have an MK 1100 x2 AH router and I have configured two wan with a simple fail-over with differents distance (Distance 1 and 2).
The traffic leaves by WAN1 and if it cuts, by WAN 2.
I want my DDNS to go through the WAN 2. I configured the script and I ran it but it does not work.

If I disconnect wan 1, and wan 2 becomes active, I can access the DDNS allright.

Is it possible that I can access through DDNS with WAN 1 active?

WAN1 its ISP and WAN2 its BRIDGE.
According to what I understand if I change the WAN1 by Bridge I will be able to configure the DDNS on that but it is not what I want