My internet speed was really bad/slow on the nintendo switch so I did a lot of research and work to improve the internet speed. Please see below on how to increase latency for the Nintendo Switch!
1. Don't use WIFI, If using a Nintendo Switch dock without a built-in LAN port, get a USB LAN adapter to establish a wired internet connection.
2. If on WIFI, reconnect to your WIFI by turning off WIFI, then turning it back on!
3. Move your switch and router closer together in proximity.
4. Change DNS. Enter the number 8.8.8.8 under Primary DNS and 8.8.4.4 under secondary DNS
5. Ensure 5Ghz WIFI, not 2.4Ghz WIFI.
6. Test your WIFI bands to choose the best channel.
7. Change MTU setting from 1400 to 1500 in settings, this will increase your packet size by 6.66%
Hoppe this helps!