You are unable to link a Nintendo Account to your Nintendo Switch console and receive the error code 2155-8006.
This error code indicates an issue with the DNS used, or that the connection timed out.
This error may be the result of a slow Internet connection, wireless interference, or a weak wireless signal from the router.
Restart the Nintendo Switch console.
Hold the POWER Button down for three seconds, and then select "Power Options" followed by "Restart."
Manually enter an alternate DNS.
If the DNS you are attempting to use is not working, entering an alternate DNS may resolve this issue.
Move the Nintendo Switch console closer to the wireless router.
If possible, place the Nintendo Switch within 3 to 5 meters of the wireless router to improve the signal strength during troubleshooting.
It may be helpful to remove the Nintendo Switch console from the Nintendo Switch dock while troubleshooting, and then return the console when troubleshooting is complete.
Power cycle your home network.
Restarting your network devices may resolve this issue if it is related to the devices being unresponsive.
Move any metal objects or electronic devices away from your Nintendo Switch console and wireless router.
Metal objects and electronic devices may interfere with wireless signals. If you have any of these, such as filing cabinets, speakers, power strips, glass, or cordless phones, next to your console or wireless router, move them away.
If supported by your router, connect to a different wireless band.
Many routers support both the 2.4Ghz and 5Ghz frequency bands. If your router supports both, set up a new Internet connection and connect to the band you are not currently connecting to. Many routers will have default SSID names that label whether the connection is 2.4Ghz or 5Ghz, but if you're not sure, you can review this information within your router's settings.
Situation Not Resolved:
If you are still unable to connect, this may indicate an issue related to the network environment or wireless router being used.
If you would like to continue troubleshooting potential issues related to the wireless router, contact the router's manufacturer for assistance with performing the following steps:
Updating the wireless router's firmware
Resetting the router back to its factory default settings
If you would like further assistance with the Nintendo Switch console, please contact Nintendo Consumer Support.