BUG: VMware NAT Service high CPU usage build-22060606

[jen2]

After a while, VMware NAT Service (vmnat.exe) will use 100% of a single core. restarting the service will resolve the issue. But then again after while it will start using 100% of a core. The internet will still work even when high CPU usage.

[jen2]

This is a very aggressive bug I had to make a script to restart the service every minute. But then I replaced only the file vmnat.exe from the version 17.0.2 and now it is working fine

[julianranz]

A very serious bug. I noticed it a week ago, when I updated to 17.5.0. Suddenly the vmnat.exe process started consuming 10% of the host cpu (no matter which guest I was running). After restarting the vmnat process (after a random time) the bug appeared again. The same solution worked for me: I replaced the vmnat.exe by the 17.0.0 version. Thanks!!!

PS: it's a very serious bug... it should be corrected !!!

[MPKLLC]

I have what appears to be the same bug with a possible slight variation. In my case when the VMware NAT Service is in the high-cpu-usage state, my VMs that are configured to use NAT will not connect to the internet. Restarting the VM NAT service appears to restore network access. However, after a short while, the high CPU usage returns, brings both the VM and its host to a relative crawl. If I don't restart the VM NAT service, eventually internet connectivity for the VMs is lost until the VM NAT service is restarted again, 

[scampbell999]

I am having the same problem. My computer fan is constantly running now, even when VMWare Workstation is closed.

[Hein_de_Lange]

+1

Mine also continues to consume high CPU even after VMWare workstation is closed

[MPKLLC]

Mine is the same. High CPU usage continues even after closing VMware Workstation Pro. The only way to stop it without restarting the computer is to restart the VMware NAT service.

[scampbell999]

Restarting the VMWare NAT Service did not solve the issue for me. I have to stop the service altogether. This means that VMs don't have network access, can't get OS updates, etc. which are often needed. Also, my company does not want to elevate privileges unnecessarily, nor allow us to do certain things on our host machines. That is why we have to use VMs! So we have to contact IT or request extra privileges to be able to stop the VMWare NAT Service.

[MPKLLC]

Agreed. Restarting the NAT Service does not solve the high CPU usage issue. Rather, it suppresses it for a seemingly random amount of time, but it always returns.

[lowbi]

same here. 17.5.0 build-22583795

[pstoric]

I'm having the same issue as well. Where can I get that file?

[jen2 · Accepted solution]

---

@pstoric wrote:

I'm having the same issue as well. Where can I get that file?

---

https://communities.vmware.com/t5/VMware-Workstation-Pro/High-CPU-usage-by-vmnat-exe-after-upgrade-t...

[zem_ljn1]

restart vmnat service resolved this issue on my Windows 10

[Simple07]

I have noticed that if you restart the VMware NAT Service, Power Usage goes down!

[MPKLLC]

Same here. However, it has been my experience the reduction in CPU usage (and therefore, power usage) is only temporary. It usually returns to the high CPU usage state within 10 minutes or less. I can't speak for anyone else, but restarting the service is not a viable solution for my situation.

[MPKLLC]

Does the high CPU usage return awhile after you do the service restart? Mine returns a varying amount of time (10 minutes or so) after I restart the service. I haven't been able to determine if there is a correlation with the amount of time for the high CPU usage to return and the VM network usage (or anything else).

[Simple07]

I thought the effect of restarting the service might give a hint to VMware and help address this silly issue. The return back to high power usage is irregular in my case, from 5 minutes to much longer, which points towards dependencies.

[LeoDavidson]

Are VMware ever going to fix this, or are they waiting for the one year anniversary or something?

[MPKLLC]

It certainly doesn't seem like they care. I've received no communications from them even acknowledging the issue let alone a fix. I suppose you have to pay for software support/maintenance to get assistance...even when it's demonstrably their issue with v.17.5.0 release.

[versat]

I also still see the bug with the latest update 17.5.1 of VMWare Workstation. Even with no VM running, VMWare NAT service completely uses one core permanently. Restarting it helps temporarily, but that can not be a solution.