Hi Ondrej,
I have no firewall enable and it's not work on all card. I have 4 port 1gbe broadcom and 4 port 1gbe intel I350 chipset based.
The clue I only have is ospf not sending hello packet between routera to routerb vice versa, both of server use HP DL360 Gen9 FreeBSD11.
Both router has multiple bgp session and receive full route from the internet.
It's weird, when routera able to send and receive ospf hello packets from and to routerc vice versa, both of them are FreeBSD11.
I'll try to reinstall the OS and configure ospf first and then one by one configure the bgp.
So, it's only happen to me? :d
Thanks anyway.