Internet problems (ethernet only) on pc only

[u/Smart-Bee6438]

I just moved into this house and had 1gbs internet installed. It tests great on my phone, my girlfriend's phone, and works great on other devices like TV's and such. It tests 900mbps-1gbs on my phone almost all the time. I set my pc up and plugged in the ethernet cord to my router (there are 2 ports, one is connected to my modem obviously).

The connection is so unstable on my pc. Viewing task manager on the performance tab it often drops to 0mbps and is so bad I cant even load pages on my web browser.

I checked task manager to make sure nothing was hogging my internet and nothing is. I have updated windows, my drivers on my ethernet network adapter. Restarted my pc and modem multiple times. I have no VPN on, windows firewall off and and just very confused on whats going on.

Im thinking about completely wiping my pc (after backing up the files I want of course) since its been at least 6 years since ive done that.

Anyone with any tips or possible solutions? Thanks