We have an Exchange environment on an HP Proliant DL380p Gen8. The VM’s came from old physical servers that were relocated to another site, ever since they were virtualized and put onto new hardware, there have been random network issues. We could ping between all Exchange servers one minute, next minute, cant ping anything.
Found an article on Microsoft site about a bug in Broadcom Chipset with HyperV and Server 2012 R2. Looked up the HP FlexLOM card, and sure enough, it uses BCM5719 chipset, one of the affected chipsets. Also the driver we are using is 16.4 and the issue was resolved in 16.8.