Regarding WAN LLB, we have 2 lines and we wanted to split traffic in two parts : mainly web surfing though WAN1 and VOIP through WAN2. I didn't manage to configure this scenario correctly because, for example, VOIP must go trough WAN2 for public SIP trunk and trough a VPN on WAN1 for internal SIP trunk between this agency and our main office.
Regarding traffic blocking, all ports where blocked, not only ICMP. Once the router was rebooted, everything went back to normal.
My guess is that I played earlier with PBR to solve the issues we add with WAN LLB and I think, even if it doesn't appear anywhere, that the router kept some traces of those PBR (did I found a bug ?).
I finally simplified the problem by just configuring WAN failover with route priority as in our main office, which works fine. KISS, as we usually say ;)
The Fortinet Security Fabric brings together the concepts of convergence and consolidation to provide comprehensive cybersecurity protection for all users, devices, and applications and across all network edges.