[SOLVED] My PC is not getting the full download speeds

[Cicada]

I recently updated my internet speeds to 300 Mbps down. Although, my PC (which is connected via Ethernet) is only getting 80-90 Mbps down whenever I run speed tests. I cannot figure this out for the life of me. I'll try to give all needed info below:
Asus ROG Strix Z390-E Motherboard
Cat5e Ethernet cable
Netgear CM700 Modem
Netgear R6700 Router

Windows 10 says my Ethernet adapter is getting Gigabit speeds
Running Windows 2004 build 19041.450
Intel Ethernet Driver version 12.18.9.23

I've tried multiple restarts, reinstalling the driver, switching the cable, and every once in a while, I get the full 300 down, but it will only last an hour or two.
I know it's not my ISP because my server is getting the full 300 consistently. It's not the router port either since my PC and server are both connected to the same switch.
I've stopped all applications in the startup menu to see if it was maybe one of my programs, but that changed nothing.

Any ideas? I'm pulling out my hair here trying to get this figured out.
Thank you in advance for any advice.

 

[sebarobbie]

I was having this exact problem some weeks ago. The only thing that solved it was reinstalling windows from a bootable USB. I still recommend you to look for new drivers or try to seek for others. This was the only solution that worked for me.

 

[kanewolf]

Check your Windows autotune settings -- https://www.ghacks.net/2016/08/05/windows-10-limiting-internet-speed/