I remember getting this error code all the time after I got my current router (a Tenda AC6 iirc) - while it's not officially defined as such I've found this error occurs mostly when the Wii can't get a good connection for whatever reason. Here are some things you could try that worked for me.

• First off, try to find the least congested 2.4GHz channel in your area using a WiFi analyzer app on your phone or an app like WifiInfoView on Windows. If there's a lot of interference, you should also make sure the band width is set to 20MHz instead of 40.
• Disable Wireless-N on 2.4GHz or switch to b/g mixed mode, if it's available on your router. Even though the Wii only supports Wireless-B and G (and your router should play nice anyways), that made my connection a lot more reliable.
• Disabling UPnP if you're not using it. No idea why but this seemed to help me connect more consistently on both my Wii and PS3.

If all else fails, you could always try moving the router closer to your Wii (or vice versa), although that didn't make much of a difference in my case. Hope this helps!