Nintendo Switch Error Code 2124-4007 — What It Means & How to Fix It

What Does This Error Mean?

The 2124-4007 error means your Nintendo Switch failed NAT traversal during an online session. NAT traversal is the process that lets your console communicate through your router to other players online. This error prevents you from joining or hosting online multiplayer games.

Affected Models

Nintendo Switch
Nintendo Switch OLED
Nintendo Switch Lite

Common Causes

Your router's NAT type is set to D or strict, which blocks peer-to-peer connections
The router's firewall is blocking the ports that Nintendo's online services need
UPnP is disabled on your router, preventing the Switch from automatically opening ports
Multiple devices on your network are competing for the same NAT mappings
Your internet provider is using carrier-grade NAT, which adds an extra layer of restriction

How to Fix It

Check your NAT type. Go to System Settings > Internet > Test Connection. Your NAT type will be shown as A, B, C, or D.

Type A or B is ideal for online gaming. Type D is the most restricted and will cause this error frequently.
Restart your router. Unplug it from power for 60 seconds, then plug it back in and wait for it to fully restart.

This clears the router's NAT table and often improves the NAT type temporarily.
Enable UPnP on your router. Log into your router's settings page (usually 192.168.1.1 in a browser) and find the UPnP option. Turn it on.

UPnP lets the Switch automatically open the ports it needs. This is the simplest fix for NAT issues.
If UPnP does not help, try placing your Switch's IP address in the router's DMZ. Find the DMZ setting in your router and enter your Switch's IP address.

DMZ removes all firewall restrictions for that device. It is safe for a gaming console. Find your Switch's IP in System Settings > Internet.
If your internet provider uses carrier-grade NAT, contact them and ask for a public IP address. Some providers offer this for free, others charge a small monthly fee.

Carrier-grade NAT means many households share one public IP. This creates an extra NAT layer that gaming consoles cannot work around on their own.

When to Call a Professional

If you are not comfortable changing router settings, contact your internet service provider. They can help configure your router for gaming or check if their network is the issue. This is a network configuration problem, not a hardware issue with your Switch.

Frequently Asked Questions

What are NAT types A, B, C, and D?

NAT type A means your connection is fully open with no restrictions. Type B has minor restrictions but works fine for most games. Type C has moderate restrictions that may cause issues. Type D is the most restricted and blocks most peer-to-peer connections.

What is UPnP and is it safe?

UPnP stands for Universal Plug and Play. It lets devices on your network automatically configure port forwarding without manual setup. It is safe for home networks and is recommended by Nintendo for the best online experience.

Why can I browse the eShop but not play online multiplayer?

The eShop connects to Nintendo's servers using a standard web connection that works through any NAT type. Online multiplayer often uses peer-to-peer connections directly between players. These peer-to-peer connections require a more open NAT type to work properly.