So this is an interesting one. We're seeing it on virtual hosts AND guests. Believe I've seen it on two hosts; both are Proliant servers running HPe NICs. One has an HPe branded Broadcom NIC, the other an HPe branded Intel NIC. We have these servers everywhere and only seeing it on two or three clients, so far. Came out of the blue, then started happening every day or two. Disable the NIC, re-enable, wait a minute, usually comes back. Had to reboot once (Or just didn't wait long enough.)
Have turned off power management in the settings on the NICs this past weekend. Doubt it'll make a difference, but no idea what else to try.