On Gig Plan but getting max only ~500Mbps to 700Mbps on speedtest.net on ethernet cat6 cable connected Windows 10 PC

Hi,

Gateway: XB8

Device: Windows 10 PC connected to gateway

Cable: cat6

Adapter: Onboard Intel gigabit adapter with last available drivers (it is a 2013 era PC)

Adapter speed setting: 1Gbps Duplex

I saw a other posts regarding this issue and also went through the post at https://forums.xfinity.com/conversations/internet/answered-troubleshooting-gigabit-internet-speeds/602da9cdc5375f08cd3e8557 but am unable to see speeds close to 1000Mbps on my wired connection to my Windows 10 PC which has a 1Gbps connection on the motherboard. The highest I have ever seen is around 700Mbps. I tried out all the ethernet ports on the XB8 gateway with multiple cat6 cables but get the same results. I am subscribed to the Gig Plan (1000Mbps when I signed up but I think it is now boosted to 1100Mbps) for a while.

When my phone connects to the gateway with WiFi 6E, I do see speeds at 1000Mbps, so it doesn't appear to be an issue with the gateway. However, I hope others who has been in the same boat before and have figured out how to get close to 1Gbps speeds on the wired PC can post what else I need to check out that is not mentioned in the article above.

As mentioned, I have tried all the ports on XB8 and have swapped out different cat6 cables too, without improvement. Unfortunately, I do not have another wired computer to see if the issue is only restricted to my computer. However, I know the onboard ethernet has 1Gbps capability and is set to Duplex mode.

Hope some of you Comcast experts and expert Users can help.

Thanks!