@jimp:
The bridging is what creates the loop, not being plugged into WAN and OPT1.
When you bridge two interfaces, you essentially bond them together and combine the WAN and OPT1 networks. Doing this once is fine, doing this twice creates a loop.
Bridged interfaces do NOT have a CARP IP assigned, and work nothing like traditional interfaces with CARP IPs, which is why there are so many warnings. Unless you deactivate the bridge somehow (STP, script, devd, etc) both bridges are always active.
Thanks for your reply. Now I understand why its creates a loop, because the bridged interfaces are both active. Then I will try using the STP method. Thanks for your help and time.