Important bit:
db:0:kdb.enter.default> bt
Tracing pid 369 tid 100130 td 0xfffff80016c02620
kdb_enter() at kdb_enter+0x3b/frame 0xfffffe0467e9a160
vpanic() at vpanic+0x19b/frame 0xfffffe0467e9a1c0
panic() at panic+0x43/frame 0xfffffe0467e9a220
trap_pfault() at trap_pfault/frame 0xfffffe0467e9a270
trap_pfault() at trap_pfault+0x49/frame 0xfffffe0467e9a2d0
trap() at trap+0x29d/frame 0xfffffe0467e9a3e0
calltrap() at calltrap+0x8/frame 0xfffffe0467e9a3e0
--- trap 0xc, rip = 0xffffffff80dadc55, rsp = 0xfffffe0467e9a4b0, rbp = 0xfffffe0467e9a4b0 ---
strlcpy() at strlcpy+0x25/frame 0xfffffe0467e9a4b0
hn_vf_rss_fixup() at hn_vf_rss_fixup+0x73/frame 0xfffffe0467e9a5b0
hn_rxvf_change() at hn_rxvf_change+0x28b/frame 0xfffffe0467e9a630
in6_update_ifa() at in6_update_ifa+0x111b/frame 0xfffffe0467e9a700
in6_ifattach() at in6_ifattach+0x487/frame 0xfffffe0467e9a840
if_up() at if_up+0x6a/frame 0xfffffe0467e9a880
ifhwioctl() at ifhwioctl+0xaf5/frame 0xfffffe0467e9a8e0
ifioctl() at ifioctl+0x475/frame 0xfffffe0467e9a980
kern_ioctl() at kern_ioctl+0x267/frame 0xfffffe0467e9a9f0
sys_ioctl() at sys_ioctl+0x15b/frame 0xfffffe0467e9aac0
amd64_syscall() at amd64_syscall+0xa86/frame 0xfffffe0467e9abf0
fast_syscall_common() at fast_syscall_common+0x101/frame 0xfffffe0467e9abf0
--- syscall (54, FreeBSD ELF64, sys_ioctl), rip = 0x802234fca, rsp = 0x7fffffffd188, rbp = 0x7fffffffd200 ---
db:0:kdb.enter.default> ps
<118>Configuring IPsec VTI interfaces...done.
<118>Configuring WAN interface...
Fatal trap 12: page fault while in kernel mode
cpuid = 3; apic id = 03
fault virtual address = 0x60
fault code = supervisor read data, page not present
instruction pointer = 0x20:0xffffffff80dadc55
stack pointer = 0x28:0xfffffe0467e594b0
frame pointer = 0x28:0xfffffe0467e594b0
code segment = base 0x0, limit 0xfffff, type 0x1b
= DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags = interrupt enabled, resume, IOPL = 0
current process = 370 (php-cgi)
trap number = 12
panic: page fault
cpuid = 3
KDB: enter: panic
So some issue in the hn driver when it's trying to bring up WAN.
Is you WAN configured in some unusual way?
You should first try diasbling all hardware off-loading if you haven't done that yet.
Steve