Since there are so many priors I'll summarize.
1. Reduce settings.
2. Optimize what you have.
3. Don't share your internet with other things.
4. Don't use WiFi, get wired.
5. For W10, always turn this off -> https://www.howtogeek.com/224981/how-to-stop-windows-10-from-uploading-updates-to-other-pcs-over-the-internet/
6. NEVER use Microsoft's Update Drivers. Get them from the maker. Use the old manual methods.
My network test reports that I have a 1% frame loss, 9.56 ms network time and a variance of 10.73 ms still gameplay lags a lot. I am playing Xcom with Long War mod not a game that requires high graphics power but still input lags by a lot.