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Jeff_Riechers's avatar
Jeff_Riechers
Copper Contributor
Mar 04, 2024

VMXnet3 Server 2025 performance issues

Had an odd one crop up today.  I updated my Server 2025 template to the 26063.1 release and then sysprepped it.  Converted it back to a new VM and network performance was .25 Mbps down.  Both on my l...
networking
J_Hawkins1460's avatar
J_Hawkins1460
Copper Contributor
Mar 08, 2024

Jeff_Riechers Delete your ghost NIC and your vmxnet driver. When you add the new NIC it'll poll for the actual VMware tools driver vs what it thinks works. Sysprep seems to do this in 2019+ sometimes if you don't have the drivers manually added to drivers and just VMware tools. E1000 will always work.

Karl-WE's avatar
Karl-WE
MVP
Sep 17, 2024
E1000 are not supported in some scenarios. Jeff could it be that the RSS / RSC config got compromised or receive buffers?
  • jeffriechers's avatar
    jeffriechers
    Copper Contributor
    Sep 18, 2024

    Karl-WE I don't see how. I have built machines from templates, and from ISO.  All seem to fail.  Same hardware 2022, 2019, 10 and 11, Debian and Ubuntu all run fine.  Just 2025 seems to not like vmxnet3.

     

    It is VMWare 7 still, so it could be something with that build of ESX.

    • Karl-WE's avatar
      Karl-WE
      MVP
      Sep 18, 2024

      jeffriechers thank you for sharing the additional Information.

      We can be sure that this forum is read by required people at MSFT. Nevertheless I will try to write some good people in the Networking area, also asking others if they hear about similar reports. 

       

      For now I would recommend the following:

       

      Please try to install b26100 from my.visualstudio.com. Partners usually have VS Enterprise license.

       

      With this open a SR with Microsoft Support (CSS) giving them a brief summary about

       

      1. Scale and affected users and potentially users aswell as scenario parameters.

      2. Mention repro steps en detail

      3. Expected and actual behaviour

      4. Certainly you can utilize Windows Admin Center Packet Monitor and using this tool and guidance to create a baseline of a patched Windows Server 2022 vs 2025 with vmxnet3 using the same physical NIC and portgroup / VLAN. 

       

      https://learn.microsoft.com/en-us/troubleshoot/windows-server/networking/overview-of-tcpip-performance?source=recommendations?wt.mc_id=MVP_338345

       

       

      At a later time it will make sense to open a support ticket with Broadcom VMware Support. Not sure if this model exists but TSAnet allows Microsoft and 3p or OEM to joint forces working on the matter.

      I would wait for the response of Microsoft Support first.

       

      Usually Microsoft Support is not for RCA (root cause analysis) and suppose break and fix, which means it worked once and broke.

       

      Since this is a new OS, and WS 2025 is in a kind of release preview state (RTM), also available through trial downloads, I believe there's a good chance for finding a solution here.

      It's in everyones interest if this is easily reproducible.

       

      I hope I got the important bits right and thank for your time and patience. You will need patience for this. 

       

      We can also keep in touch via DM and Teams about that.

       

      Instead of templates as I assume sysprepped, please install VMs fresh with the respecticely latest ISO dl at Microsoft and update before testing. 

       

      Sysprep can bring own vibes. Rather watch out to enable VBS and having the latest VMware Tools installed. 

       

      OT:

      I have heard there's a new supersedence device coming for vmxnet3.

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