VLAN interfaces keep dropping traffic

I am using FreeBSD with several VLAN interfaces, but it seems to randomly drop all traffic on the VLAN interfaces and the only way to fix it seems to be to restart networking, re-apply all of the settings to the VLAN interfaces and destroy then re-create them all. I have been completely unable to find anything in any log files when this happens so I am lost on what the cause would be.

How to ask questions the smart way; Be precise and informative about your problem

You're not giving us a lot to go on. What version of FreeBSD? What interface? What have you tried to fix the problem?

What hardware is FreeBSD integrating to, e.g. Cisco, HP, Juniper, D-Link, etc...

Is this FreeBSD installation on physical hardware or a VM guest?