It might be best to use the settings described here [SQM/QOS] Recommended settings for the dslreports speedtest (bufferbloat testing) - Installing and Using OpenWrt - OpenWrt Forum to make sure you are testing consistently each time while making changes. You can select which test servers to use so it uses the same servers for each test run.
Since you have an R7800, you might want to try this community build Build for Netgear R7800 - Community Builds, Projects & Packages - OpenWrt Forum based on the latest master branch of openwrt if you're interested in running the latest code.