Windows Slow Upload Speeds Over Ethernet

After installing the May 2023 updates, I noticed slow upload speeds of large files (500m+) to OneDrive.

I have 100/100 internet speeds. That file should upload in seconds, not hours.

After rebooting my router and switch, I saw no difference in upload speeds. I also checked for new drivers, and there were none.

I wanted hard numbers to work with and rule out a problem with OneDrive. I ran speedtest and found my speeds were 100/.2 to 100/.5. That’s not a typo!

I switched the system to Wi-fi and ran speedtest again. My speeds were 50/50.

At this point, I’m thinking my Ethernet card is going bad. I did some Googling and found a post, which I can’t locate now, that pointed to changing properties on the Ethernet device. Go to Device Manager–>Network Adapters–>[Your Ethernet Controller}. Right click and select Properties. Set each of the following properties to Disabled: Large Send Offload (IPv4}, Large Send Offload v2 {IPv4), and Large Send Offload v2 {IPv6}.

My Wi-Fi speed remained the same, which was expected. My Ethernet speed was now 100/100 on multiple tests.

I don’t know why it worked. I don’t why it changed, but I suspect the May 2023 Windows Updates changed these properties or changed the behavior when these properties were Enabled.

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