Thats because you are using NVENC. Look at the bottom of my last post, i told you what settigns to use. They will give you better quality, but they are not causing your dropped frames. That is your internet.
Have you tried restarting your router/modem? Also take the
twitch bandwidth test. Just raw upload speed means little it has to be extremely consistant even if your connection drops for a fraction of a second you can loose some frames.
Make sure you have tried everything else mentioned on
the thread a sent you previously.
If you are still having problems it could be caused by your ISP and you would have to contact their customer support about that.