Not able to raise the MTU on FreeBSD 10.3

[Wayne H]

I have two new servers connected together with  10 gig Intel and  1 gig Nic cards. It doesn't matter if I have them connected via a switch or directly connected to each other. I am unable to pass ping packets above 1472. If I set the MTU to anything up to 9000 I till can't pass anything above 1472. I have the 10 gig connected via an Intel SFP+ Cable between the servers. I also tried connecting the 1 gig Nics between the servers.

I would like to use jumbo frames to mount these servers to a NFS server. If I set the MTU to 9000 in rc.conf on boot up I can mount the NFS but as soon as I try to write to it the NFS hangs. If I umount and reset the MTU to 1500 it works fine.

Anyone know what I am doing wrong?

root at backgate1:/usr/home/wayne # ping -D -s 1472 10.168.48.145
PING 10.168.48.145 (10.168.48.145): 1472 data bytes
1480 bytes from 10.168.48.145: icmp_seq=0 ttl=64 time=0.111 ms
1480 bytes from 10.168.48.145: icmp_seq=1 ttl=64 time=0.059 ms
^C
--- 10.168.48.145 ping statistics ---
2 packets transmitted, 2 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 0.059/0.085/0.111/0.026 ms
root at backgate1:/usr/home/wayne # ping -D -s 1473 10.168.48.145
PING 10.168.48.145 (10.168.48.145): 1473 data bytes
ping: sendto: Message too long
ping: sendto: Message too long
^C
--- 10.168.48.145 ping statistics ---
2 packets transmitted, 0 packets received, 100.0% packet loss

FreeBSD 10.3-RELEASE #0 r297264: Fri Mar 25 02:10:02 UTC 2016     root at releng1.nyi.freebsd.org:/usr/obj/usr/src/sys/GENERIC

Intel(R) Ethernet Connection XL710 Driver, Version - 1.4.3

ixl0 at pci0:5:0:0:        class=0x020000 card=0x00078086 chip=0x15728086 rev=0x01 hdr=0x00
    vendor     = 'Intel Corporation'
    device     = 'Ethernet Controller X710 for 10GbE SFP+'
    class      = network

ntel(R) PRO/1000 Network Connection, Version - 2.5.3-k
    
igb0 at pci0:11:0:0:       class=0x020000 card=0x152115d9 chip=0x15218086 rev=0x01 hdr=0x00
    vendor     = 'Intel Corporation'
    device     = 'I350 Gigabit Network Connection'
    class      = network

ixl0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 9000
        options=6407bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,TSO4,TSO6,LRO,VLAN_HWTSO,RXCSUM_IPV6,TXCSUM_IPV6>
        ether 3c:fd:fe:9d:5c:24
        inet 10.168.48.144 netmask 0xffffff00 broadcast 10.168.48.255
        nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
        media: Ethernet autoselect (10Gbase-Twinax <full-duplex>)
        status: active

igb0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 9000
        options=403bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,TSO4,TSO6,VLAN_HWTSO>
        ether 0c:c4:7a:32:f0:51
        inet 172.16.48.244 netmask 0xffffff00 broadcast 172.16.48.255
        nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
        media: Ethernet autoselect (1000baseT <full-duplex>)
        status: active

Thanks