Green Cloud and others in the community have discovered that a recent Microsoft update (KB4088875) is causing network issues for a specific subset of Virtualized Servers. The symptoms of this issue are:
- Assigned private IP’s on a VM are lost causing loss of connectivity
- VXNET2/3 Network Adapters on a VM disappear
- New Network Adapters appear appended with #2 (or #3, etc)
- IP conflicts are present when attempting to re-assign IP’s to new NICs
Only VMs with both of the following attributes appear affected at this time:
- OS: Windows Server 2008 R2 or Windows 7
- NIC: VXNET3 or VXNET2
Servers with other NICs or operating systems appear unaffected.
To resolve this issue, please perform the following steps:
- Open Command Prompt (WIN+R, type “cmd”, Enter)
- Enter “set devmgr_show_nonpresent_devices=1”
- Close Command Prompt.
- Open Device Manager (WIN+R, type “devmgmt.msc”, Enter)
- View > Show Hidden Devices
- Under networking, delete the grayed out VXNET3 NICs.
- IP’s can now be re-assigned on new NIC.
- If errors persist, reboot the machine and then try reassigning the IPs.
Please note that the inactive NICs must be removed, since re-assigning a new IP will cause a conflict if the inactive NICs are still present. VMs on DHCP may not be affected, but the inactive NICs should be removed anyway to avoid future issues (this may cause an IP change due to a new MAC address).
For further information please see the following: