How to migrate CT from Proxmox 1.9 to 3.3 (network issue)

[raid]

I would share my experience.

Scenario:
Server 1: OVH, proxmox 1.9 with 2 CT, 1 IP + 2 IPFailover, shorewall with NAT and Firewall, no mailserver
Server 2: OVH, proxmox 3.3 , 1 IP, no shorewall, default proxmox networking model, proxmox firewall inactive at moment, no mailserver
Shared NAS

Target:
Quickly migrate all containers from server1 to server 2

Steps: (if needed, steps 1 and 2 can be reversed)

CT1 migration (10GB):
1) vzdump (25 min)
2) stop CT1 (to avoid new database entry)
3) vzrestore on server 2 (5 minutes)
4) start CT1 on server 2
5) test CT1 (could be usefull a second IP) if fails start CT1 on SERVER 1 else goto next step
6) Point first IPFailover to new server

CT2 migration (50GB)
1) stop CT1 (to avoid new database entry)
2) vzdump (45 min)
3) vzrestore on server 2 (35 minutes)
4) start CT2 on server 2
5) test CT2 (could be usefull a second IP) if fails start CT2 on SERVER 1 else goto next step
6) Point second IPFailover to new server

Problem:
I get only a networking problem on step 5, the OUTbound connection are KO, the CT doesn't ping outside the host.
I suppose it's related to the different network configuration from server1 and server2

Solution:
comining soon (Any tip?)