Hi tabia tabz, Nintendo has an excellent walk-through on fixing just that issue. Instead of just re-ryping their information I will post it exactly as they had it because they offer very nice images of exactly what you need to do each step which should help you alot.
Here is what Nintendo states:
Error Code: 051099
Was this information helpful?Unable to use your wireless signalLikely cause:
It appears that the settings entered into the Nintendo DS are not compatible, or the router's broadcast settings should be changed.How to fix:
Try creating a new connection with your system. Nintendo DSi owners trying to play multiplayer games will want to be sure to read the "Trying to play online multiplayer with Nintendo DSi."
- Create a new connection: This error can occur if a setting (like your network's name) has changed since you last connected. If it's been awhile since you connected, or if this is your first time connecting, creating a new connection file will often resolve this error code. Click the button below for your system and we'll walk you through the connection step-by-step.
- Trying to play online multiplayer with Nintendo DSi
Even if you are able to connect online and use other online features of the Nintendo DSi, if you are attempting to play multiplayer games but are receiving error code 51099 when you try and connect, then your router is likely using a security type - WPA - that is not compatible with Nintendo DS Game Cards.Try this:
If you are sure you are using WPA, click here for more information including alternative connection methods. If you're not sure if you're using WPA, you can find out by going into the connection settings on your Nintendo DSi and doing a search for an access point. Follow these steps:
- Turn on your Nintendo DSi and access the System Settings by clicking on the wrench icon.
- Scroll over to the third page, and select "Internet."
- Now choose "Connection Settings."
- Click on "None" for "Connection 1."
- Click on "Search for an Access Point."
- The Nintendo DSi will search for any wireless networks within range. Once it is finished searching, it will display the names of all the wireless networks it finds.Look for your wireless network.
- What to do next will depend on the "lock" icon you see next to your network on the Nintendo DSi.
No security - This connection type is compatible with Nintendo DS Game Card online multiplayer.
WEP - This connection type is compatible with Nintendo DS Game Card online multiplayer.
WPA - This connection type is not compatible with Nintendo DS Game Card online multiplayer. Security will need to be changed to WEP or turned off in order to play online. Click here for more info.
- Other suggestions:
- Make sure your router is set to broadcast in "b" or "mixed" mode. If your wireless router is transmitting in "N" only mode, you will need to switch it to "b/g" or "mixed" mode. For help accessing your router's settings, click here and select your router brand and model (if available). Most routers will have this setting in the "broadcast settings" menu.
- Check for wireless interference, which can affect the signal strength to the Nintendo DS. To help minimize wireless interference, try the following:
- Make sure other wireless devices such as cordless phones or wireless speakers are turned off, and that the Nintendo DS is an open area without objects or electronics blocking the signal.
- Change your router's channel setting to 1 or 11. By default, most routers broadcast on channel 6, which overlaps with other channels and may be weaker. For help doing this, click here and select your router brand and model (if available). The information you need is found in the "Broadcast Channel:" area.
We can help! We have found that simply erasing the old connection file and creating a new connection to your router may help. Click the button below for a step-by-step guide. If at the end you still need help, you'll find contact information to reach our specially-trained representatives. Click the button below for your system and we'll walk you through the connection step-by-step.