IPV6 and Bridge, losing IPV4 ?

[Guldil]

Hy,

i'm trying to use ipv6 from my ISP (Free ADSL in France).
One of the solution is to bridge WAN & LAN and create a new interface just for ipv6 trafic, WAN will handle only ipv4.

This solution is working with pfsense 2.1.3 but after 5 - 10min i'm losing connectivity for ipv4 !
but ipv6 still working !!!
I have to go to WAN interface, hit "save" and "apply" ipv4 is back but just for 5 min…

What can be the origin?

Thanks,

Guldil