Guest windows 10 network speed very slow vs host

[tsdev1]

Hi,

I'm running a iMac Pro with macOS Big Sur 11.6. It has 32 gig of ram and 8 core. On the host, I continue to run speed and packet loss tests which consistently provide 800 meg + results (have 1 gig business class speed from Comcast). The host is hard wired and not on wifi.

I have several guest windows 10 vms running on this host and each is only able to speed test out roughly 100 to 250 meg at most. Multiple seem to lose packets during a packet loss test. I've shut down all but one (brand new win 10 vm with nothing on it but the browser and the same results - roughly 200 meg).

Is there a reason why the guest machines would have such low bandwidth when the host is receiving 4 times the speed? The networks are set for 1 gig on the guest machine.

Thanks in advance for help with this,

TS

[Mikero]

Does the issue persist with Non-Windows guests as well?

Does the issue persist with both NAT and Bridged, or just one or the other?

Which Mac, and how is it hardwired?

[Mikero]

Also, what tools are you using to test the packet loss and bandwidth?

[tsdev2]

Thanks for the reply. its an imac pro (2017). I've tried multiple network settings. To test this im ussing packetlosstest.com and also different speed test sites such as xfinitiy and fast.com.

I have not tried with other guest operating systems - just windows 10.

[tsdev2]

It's hardwired via ethernet cable. The host speed tests out near 1 gig without packet loss from the multiple days of testing and the guest on the same system bandwidth is in the 150 - 250 range when running the same tests using the same websites.

[tsdev2]

Is the expectation correct that if I'm getting nearly 1 gig on the host that the guest systems should run equally or near the same?

[gringley]

I have a similar configuration and cannot reproduce this issue when bridged to the Ethernet interface.  In my case Ookla Speedtest can get the full 400+Mbps out of my ISP either from the Windows 10 guest or the iMac Pro host.  On the other hand the bridge to WiFi is still broken and unusable.  Any ideas when the NAT flag thing will be fixed with the bridged interfaces?

[tsdev1]

What is also strange is that if I turn wifi on the iMac host and unplug the ethernet the speeds seem to be the same or faster (still not more than 350 meg) but does not make any sense the hard wired host receives 850 meg+ when using ethernet and guests are in the 200 or less range?

Is there anything that can be done - very painful and I don't remember this being so slow before upgrading to version 12

[tsdev1]

Is there any way to troubleshoot this with someone on the Vmware technical support side? When I try to work through support it won't show the Fusion product for some reason in my profile to submit a support request.

I'm considering buying a new iMac Pro ahead but may not if VMware Fusion guest bandwidth is going to continue to be this poor (in the 100 meg range when the host is in the 900 meg range). If so - I may go back to Lenovo and drop Fusion going back to vm workstation.