Thank you for your answer. In my case, the extra.lzma for loader 1.03b_mod ds3617 DSM 6.2.2 v0.5_test is not work for virtio ethernet nic.
$ cat /etc/rc.modules
EXTRA_MODULES="crc-itu-t crc-ccitt dca mii mdio libphy atl1 atl1e atl1c alx uio ipg jme skge sky2 ptp_pch pch_gbe qla3xxx qlcnic qlge netxen_nic sfc e1000 pcnet32 vmxnet3 bnx2 libcrc32c bnx2x e1000e igb igbvf ixgbe ixgbevf r8101 r8125 r8169 r8168 tg3 usbnet ax88179_178a button evdev ohci-hcd ehci-hcd ehci-pci atl2 e100 igbvf ixgb forcedeth tn40xx be2net cxgb cxgb3 cxgb4 atlantic bna vxge aqc111 asix cx82310_eth et131x i40e i40evf mcs7830 pegasus plusb r8152 rtl8150 s2io xgmac virtio virtio_pci virtio_ring virtio_net virtio_blk"
$ ls /usr/lib/modules/update/virtio*
/usr/lib/modules/update/virtio_balloon.ko /usr/lib/modules/update/virtio_console.ko /usr/lib/modules/update/virtio_mmio.ko /usr/lib/modules/update/virtio_pci.ko /usr/lib/modules/update/virtio_scsi.ko
/usr/lib/modules/update/virtio_blk.ko /usr/lib/modules/update/virtio.ko /usr/lib/modules/update/virtio_net.ko /usr/lib/modules/update/virtio_ring.ko
$ dmesg | grep 'virtio'
[ 526.653527] virtio-pci 0000:06:03.0: setting latency timer to 64
[ 528.391896] virtio_console: Unknown symbol hvc_remove (err 0)
[ 528.391935] virtio_console: Unknown symbol hvc_kick (err 0)
[ 528.391958] virtio_console: Unknown symbol hvc_alloc (err 0)
[ 528.391979] virtio_console: Unknown symbol hvc_poll (err 0)
[ 528.392089] virtio_console: Unknown symbol hvc_instantiate (err 0)
[ 528.392117] virtio_console: Unknown symbol __hvc_resize (err 0)
[ 571.290649] virtio_console: Unknown symbol hvc_remove (err 0)
[ 571.290698] virtio_console: Unknown symbol hvc_kick (err 0)
[ 571.290722] virtio_console: Unknown symbol hvc_alloc (err 0)
[ 571.290744] virtio_console: Unknown symbol hvc_poll (err 0)
[ 571.290770] virtio_console: Unknown symbol hvc_instantiate (err 0)
[ 571.290794] virtio_console: Unknown symbol __hvc_resize (err 0)
Maybe some steps of mine were wrong. Could you tell me about more detail of operation procedure?