I set up VyOS rolling from 2020-02-24 on a xcp-ng 8 host. When trying to assign an IP to an ethernet interface, it errors out when ethtool tries to set flow control settings (pause/etc). Looking at the source, there are a list of blacklisted drivers for pause, but xen_netfront is not on the list. After adding it, the interface comes up without issue.
Pull request:
https://github.com/vyos/vyos-1x/pull/266