Disable all packet filtering => get public IP on LAN if ?

[dood]

Hi everyone,

Just get a Pfsense running on my fiber internet acces.

WAN connection is configured in PPPOE mode, pfsense shows my public IP : looks good
LAN connection is on the WAN IF of our Sonicwall TZ105 (firewall appliance which is just behind).

Why am i doing that : because our internet access provider need a PPPOE authentication while using a specific VLAN (835).
Pfsense know how to do that fine and not my Sonicwall :)

But here is my issue :

I build an IPSEC VPN through my Sonicwall and another one which is in a datacenter. (IPsec functionnality of the Pfsense is not used and is not an option)
Since i put my Pfsense box, VPN takes maybe 5 minutes to mount, it looks like that something is wrong during phase 1 (remote party timeout). NAT-Traversal is enabled on my 2 Sonicwall.

So i was thinking about using this option on pfsense :
"Disable all packet filtering"

If i'm using this option does the WAN IF public IP is mapped on the LAN IF ?
If someone have any other idea about that, you're welcome

Thx