pfSense is not a proxy appliance. Note that "disabling" IPv6 on pfSense will do nothing for the clients that get IPv6 RAs etc. from your real router and so will resolve IPv6 first.
This is not a pfSense issue or Squid issue, at all.
of course. i've resolve the problem adding a second network interface. So the lan is in my lan segment, and the was is in external network.
now works everything (a bit slow, i'm working on it).
it was a network problem definitely.
Thanks to all!