opnsense does not respond to sip options

[Silver77]

Hello to all. i don't understand why opn doesn't reply to options packages. I see the packets enter but do not go back. some idea? ip packets arrive at the pbx.
the pbx is behind nat

[larsd]

is your pbx replying?

[Silver77]

Yes ..
I did some packet capture, and I understand what happens, but I don't understand why.  i configured 2 wan with failover and i saw that option packets come in from the first connection and leave the second.  if I check which connection the pbx navigates with, I see that it is on the first one ...
now I have changed the configuration type and fixed the problem, but I would have liked to understand why this behavior.