Does keep state modify packet anyhow?

[Roman Gorohov.]

Hello, list.


I have a strange problem, we work with one application that connecting to remote server at start-up(and remote server connect back to the app). 
The problem is, that when I uncomment keep state option in rule:
pass from $lan #keep state
in pf.conf its seems that remote server can't connect back...

I've checked many times, its depends only on that option, how might that be?

Regards, Roman.