Review on High-Speed USB 3.0 Ethernet Adapter for Nintendo Switch - 1G Gigabit Ethernet LAN Network Dongle Converter, CableCreation RJ45 to USB A Wired Internet Connection for MacBook, Xiao Mi Box, PC by Joseph Flamm

I bought this because I was tired of dealing with lag while playing Smash Bros online. This works pretty well. The only problem is that I will still have occasional connection issues (very rarely). For me it shows up on boot which is usually fast but sometimes won't connect or takes a little time. I have fiber optics so it could be a signal but it's unlikely. Maybe you could find a better one for more bucks, but this works for me and my limited usage app.