On the XenServer hypervisor, if we deploy the 64-bit version of VyOS 1.1.7 on a VM with 512MB RAM we see loads of the following errors logged regularly:
xen_netfront: xennet: skb rides the rocket: 19 slots
This appears to be caused by a kernel bug, see https://bugs.launchpad.net/ubuntu/+source/linux-lts-raring/+bug/1195474
We also measure packet loss via the router, but not until it has been up for a few days (it's fine straight after a reboot for some reason).
Switching to the i586-virt image fixes the problems - we don't see any indication of these errors or any packet loss when using that image.
The suggested workaround (disabling scatter gather on the NICs) seems to stop the errors being logged but doesn't fix the packet loss issue for us (only reboot or switching to 32-bit virt image stops the packet loss).