This page explains how to set up an Internet connection on Nintendo Switch and the components necessary to do so. There is also a troubleshooting guide tailored to specific setups.
Unable to connect to Online. Latest CFW and tested internet connection and servers. Happened after I updated firmware I believe, didn't really tried before. Any help? : r/SwitchPirates
Switch] What are the USB ports on the Nintendo Switch dock used for?, Q&A, Support
What to do if Switch won't connect to Internet or Wi-Fi? - Android Authority
Everything you need to know about Nintendo Switch Online
TALK WORKS Network Cable Compatible w/Nintendo Switch OLED - 10 ft/3 m Long, Cat7 RJ45 Ethernet Cable-Fast Transmission for Stable Internet Connection & Gaming-Durable Cable for Multiplayer Games : Video Games
Internet connection (with a wireless connection), Nintendo Switch Support
Wired Internet connection; Help compatible with Nintendo to get stable and consistent LAN connectivity 10/100M network speed Connector: USB 2.0 to
Ethernet USB LAN Adapter fits Nintendo Switch
Network Error? : r/PokemonUnite
Internet connection (with a wireless connection), Nintendo Switch Support