I havinf issues with both Hub loops when ping from Spoke for FortiOS 7.6.6

when you ping the Hub-Lo from the spoke, which source address are you using ? the tunnel IP if any is set or a Loopback on the Spoke?

can you confirm via sniffer and/or diag debug that traffic originating from Spoke towards the Hub, on the Hub is visible/reaches the FGT ? 

I assume that routes are correctly advertised by each FGT

also, are firewall rules in place that grants/permits this traffic ?

FG120G_Hub # diagnose debug flow filter addr 10.6.0.254

FG120G_Hub # diagnose debug flow filter proto 1

FG120G_Hub # diagnose debug flow show console enable

G120G_Hub # diagnose debug enabl

FG120G_Hub # diagnose debug flow trace start 10

!

FG120G_Hub # id=65308 trace_id=1 func=print_pkt_detail line=6336 msg="vd-root:0 received a packet(proto=1, 169.254.40.11:10->10.6.0.254:2048) tun_id=169.254.40.11 from ISPbWIN2. type=8, code=0, id=10, seq=0."

id=65308 trace_id=1 func=ipsec_spoofed4 line=221 msg="src ip 169.254.40.11 match selector 0 range 0.0.0.0-255.255.255.255"

id=65308 trace_id=1 func=init_ip_session_common line=6550 msg="allocate a new session-000019d5"

id=65308 trace_id=1 func=__vf_ip_route_input_rcu line=2116 msg="find a route: flag=80000000 gw-0.0.0.0 via root"

id=65308 trace_id=1 func=__iprope_tree_check line=524 msg="gnum-100004, use int hash, slot=111, len=2"

id=65308 trace_id=1 func=fw_local_in_handler line=630 msg="iprope_in_check() check failed on policy 0, drop"

id=65308 trace_id=2 func=print_pkt_detail line=6336 msg="vd-root:0 received a packet(proto=1, 169.254.40.11:10->10.6.0.254:2048) tun_id=169.254.40.11 from ISPbWIN2. type=8, code=0, id=10, seq=1."

id=65308 trace_id=2 func=ipsec_spoofed4 line=221 msg="src ip 169.254.40.11 match selector 0 range 0.0.0.0-255.255.255.255"

id=65308 trace_id=2 func=init_ip_session_common line=6550 msg="allocate a new session-000019da"

id=65308 trace_id=2 func=__vf_ip_route_input_rcu line=2116 msg="find a route: flag=80000000 gw-0.0.0.0 via root"

id=65308 trace_id=2 func=__iprope_tree_check line=524 msg="gnum-100004, use int hash, slot=111, len=2"

id=65308 trace_id=2 func=fw_local_in_handler line=630 msg="iprope_in_check() check failed on policy 0, drop"

id=65308 trace_id=3 func=print_pkt_detail line=6336 msg="vd-root:0 received a packet(proto=1, 169.254.40.11:10->10.6.0.254:2048) tun_id=169.254.40.11 from ISPbWIN2. type=8, code=0, id=10, seq=2."

id=65308 trace_id=3 func=ipsec_spoofed4 line=221 msg="src ip 169.254.40.11 match selector 0 range 0.0.0.0-255.255.255.255"

id=65308 trace_id=3 func=init_ip_session_common line=6550 msg="allocate a new session-000019de"

id=65308 trace_id=3 func=__vf_ip_route_input_rcu line=2116 msg="find a route: flag=80000000 gw-0.0.0.0 via root"

id=65308 trace_id=3 func=__iprope_tree_check line=524 msg="gnum-100004, use int hash, slot=111, len=2"

id=65308 trace_id=3 func=fw_local_in_handler line=630 msg="iprope_in_check() check failed on policy 0, drop"

id=65308 trace_id=4 func=print_pkt_detail line=6336 msg="vd-root:0 received a packet(proto=1, 169.254.40.11:10->10.6.0.254:2048) tun_id=169.254.40.11 from ISPbWIN2. type=8, code=0, id=10, seq=3."

id=65308 trace_id=4 func=ipsec_spoofed4 line=221 msg="src ip 169.254.40.11 match selector 0 range 0.0.0.0-255.255.255.255"

id=65308 trace_id=4 func=init_ip_session_common line=6550 msg="allocate a new session-000019e2"

id=65308 trace_id=4 func=__vf_ip_route_input_rcu line=2116 msg="find a route: flag=80000000 gw-0.0.0.0 via root"

id=65308 trace_id=4 func=__iprope_tree_check line=524 msg="gnum-100004, use int hash, slot=111, len=2"

id=65308 trace_id=4 func=fw_local_in_handler line=630 msg="iprope_in_check() check failed on policy 0, drop"

id=65308 trace_id=5 func=print_pkt_detail line=6336 msg="vd-root:0 received a packet(proto=1, 169.254.40.11:10->10.6.0.254:2048) tun_id=169.254.40.11 from ISPbWIN2. type=8, code=0, id=10, seq=4."

id=65308 trace_id=5 func=ipsec_spoofed4 line=221 msg="src ip 169.254.40.11 match selector 0 range 0.0.0.0-255.255.255.255"

id=65308 trace_id=5 func=init_ip_session_common line=6550 msg="allocate a new session-000019e7"

id=65308 trace_id=5 func=__vf_ip_route_input_rcu line=2116 msg="find a route: flag=80000000 gw-0.0.0.0 via root"

id=65308 trace_id=5 func=__iprope_tree_check line=524 msg="gnum-100004, use int hash, slot=111, len=2"

id=65308 trace_id=5 func=fw_local_in_handler line=630 msg="iprope_in_check() check failed on policy 0, drop"

and excate ping from the Spoke to the Hub