Network Connection Issues with Hyper-V Host and VM's

A few of our clients started to have strange network connection issues starting a few months ago at random times. I wanted to see if anyone is having the same issue or could shed some light into what is going on. We have a consistent setup among our client this is only happening to a few. Thanks!


Either both the Hyper-V host and the VM's will lose network connection (internet and LAN communication) or just some of the VM's.


- All servers are Dell's with 2 Broadcom Network Adapters. Network Driver/firmware and Windows updates are up to date with latest.
- All servers are using Teamed Adapters in Switch Independent mode and dynamic load balancing
- HyperV host shares vSwitch for ManagementOS and VM’s
- Basic out of the box Hyper-V setup and not clustering


-      Some or all VM’s will lose network communication with other servers, desktops and the internet
-      The network adapters on the Host and VM’s don’t display any issues right away and eventually will say no internet access
-      Hyper-V host is unable to ping default gateway, the VM’s, or any public IP address. Team and both NIC’s do not display any issues are show as up. At times, I am still able to initial a remote connection to the HV host even though the HV host can’t communicate to the internet and can’t ping the gateway.

Temporary resolution:

I am able to resolve the issue by disabling one of the network adapters and re-enabling. Network communication comes back.


The only thing I can see in the event log in the following Event

Log Name:      System
Source:        Microsoft-Windows-MsLbfoSysEvtProvider
Date:          7/14/2015 9:54:55 AM
Event ID:      16945
Task Category: None
Level:         Warning
Keywords:      Classic
User:          N/A
Computer:      HV-01
MAC conflict: A port on the virtual switch has the same MAC as one of the underlying team members on Team Nic Microsoft Network Adapter Multiplexor Driver
Event Xml:

Running a Get-NetAdapater shows that there are the same MAC addresses however, other servers that are working fine show the same. I manually set all of the MAC addresses to something different but still get the event log entry and still have the same issue.

Name                      InterfaceDescription                    ifIndex Status       MacAddress             LinkSpeed
----                      --------------------                    ------- ------       ----------             ---------
NIC1                      Broadcom NetXtreme Gigabit Ethernet #2       13 Up           F8-BC-12-4D-35-AE         1 Gbps
vEthernet (SWITCH-01) Hyper-V Virtual Ethernet Adapter #2          21 Up           F8-BC-12-4D-35-AE         10 Gbps
Hyper-V Team              Microsoft Network Adapter Multiplexo...      18 Up           F8-BC-12-4D-35-AE         2 Gbps
NIC2                      Broadcom NetXtreme Gigabit Ethernet          12 Up           F8-BC-12-4D-35-B0         1 Gbps
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Philip ElderTechnical Architect - HA/Compute/StorageCommented:
Turn VMQ off for all Broadcom Gigabit ports. This is a known issue with Broadcom Gigabit NICs.

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
dougholdAuthor Commented:
Thanks! This is exactly what the issue was.
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today

From novice to tech pro — start learning today.