Hi,
there is only a tunnel between Site A 172.16.1.0/24 and site B (lan) 172.16.2.0/24!
ping failed because of missing tunnel. Ipsec is not routed.
U need to add parallel tunnel on both sites for Network 10.5.1.0.
Site A 10.5.1.0/24 (lan) <–-> site B (lan) 172.16.2.0/24
If u want to route VPN traffic use OpenVPN.
you cant access networks over a vpn from pfsense itself by default, it looks like thats what you are doing.
Yes, thats caused by Freebsd ipsec implementation.
u need to set source ip (interface) or u need to define a static route.
Remember Lan ip must match tunneldefinition to work.
ping -S <lan ip=""></lan>
cya