We have Hyper-V on Windows server 2012 R2, where was deployed several hosts with FreeBSD. That is used as the gateway, VPN server, web server, and other. We don't use the legacy network adapter.
On all machines with a certain periodicity network interfaces are stopping with error "no buffer space are available".
Helps only ifconfig down/up.
The network driver for Hyper-V before 10.3 is buggy, and becomes unstable even under slight load. Please update to 10.3 or 11.0 if you only want to stick to releases. Current, 11-stable, and 10-stable are also in good shape for Hyper-V support.