Windows 10: Very slow up/download speeds with HyperV external switch setup

A long standing issue for many Hyper-V users is when you set up an external wifi switch in Hyper-V, it kills the download and/or upload speeds. On my ASUS with an Intel NIC, my uploads and downloads are only 2% of normal speeds making internet virtually useless. The problem does not arise with the default switch but that is behind a NAT which makes it very difficult to RDP direct to VM. I have found a solution that works for me, and I am now back at full speed. Slow download - disable packet coalescing on the wifi card settings in device manager. Slow upload - disable large send offload (for IPV4 and IPV6) from the external vethernet switch that is bridged (not the default vethernet switch). I have no idea if this works for other network adaptors but seems to work for Intel NICs. Source of information (credit to Mike in post #6). virtualization - Creating an external virtual switch on Hyper-V causes host to experience very slow networking - Super User

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Slow download speed after creating Hyper-V External Virtual Switch

Have you set the number of cores to 8 in hyer-v settings (virtual processor). No idea otherwise.

 

Slow download speed after creating Hyper-V External Virtual Switch

Hello.
After buying a new PC (its specs are on my profile), enabling Hyper-V and creating a new External Virtual Switch, I notice that the download speed drops dramatically. My internet conneciton is 1Gbps down and 200Mbps up.

Without External Virtual Switch:

• Speedtest (I get 944 Mbps download, and 214 Mbps upload) --> Speedtest.net by Ookla - My Results
• CPU usage while on Speedtest (no core is maxed out):

• Iperf with a host on the same LAN (upload 911Mbps, download 777Mbps):

• Lan Speed test (746 Mbps upload and 716 Mbps download):

With External Virtual Switch:

• Speedtest result (I get 378 Mbps download and 212 Mbps upload) --> Speedtest.net by Ookla - My Results

• CPU usage while on Speedtest (notice the first core is fully maxed out):

• Lan Speed Test (742 Mbps upload and 596Mbps download):

• Iperf with a host on the same LAN (upload 861 Mbps, download 583 Mbps):

• CPU usage while on Iperf (download) - Notice, once again, Core 1 fully maxed out​:

Conclusion

When the External Virtual Switch is enabled, I assume the download speed is lower due to the fact one CPU core is being maxed out, my question is why? Why isn't the load spread throughout the cores?
Is anyone experiencing a similar issue?

Regards.

 

Slow downloading speed

Hi Manthan,

Regarding your download speed issue, we found a suggestion given by Eeshwar Kumar on our Community page. You can check this link on the suggestion he provided:

Why is Windows Store's download speed so slow?

Let us know if you need further assistance.