(Rewritten on 12-3-2021.)

Important: nds-constraint does not work with this method, due to the USB Connector always having to be connected to a preset local IP. Changing this IP results in maintenance errors upon connecting.

This brief tutorial will showcase how to use Wiimmfi / AltWFC / whatevers without a WEP router or a hotspot. Keep in mind that this does make use of the Nintendo Wi-Fi USB Connector and a Virtual Machine (if you prefer to use that over real hardware), so keep those handy.

Spoiler: Requirements

• A Nintendo DS/DSi/3DS/2DS (of course)
• A Nintendo Wi-Fi USB Connector
• A computer or VM running either Windows XP or Windows Vista (use XP if you can, since it often has better results than Vista)
• Nintendo's Wi-Fi USB Connector software
• AdmiralCurtiss' WFC Patcher
  
• A WFC game that is supported by Wiimmfi or AltWFC

Spoiler: Installing the software

1. Unpack the *.zip file and run the setup. Before running the setup file, first plug in your Nintendo Wi-Fi USB Connector and make sure your Firewall is either disabled or isn't blocking the software.
2. Only for VirtualBox users: If the USB Connector isn't detected by VirtualBox straight away, click on Devices > USB > Nintendo Wi-Fi USB Connector [0001] and try again.
3. If installed successfully, a little icon that looks like this should appear every time you insert your USB Connector.

Spoiler: Changing the DNS

1. Click on the small Network icon that should be next to the Connector USB software. If it's not there, go to the Control Panel under Network Properties.
2. Click on the network that reads Nintendo Wi-Fi USB Connector (*a).
3. Select Internet-protocol (TCP/IP) > Properties (*b).
4. Select Use the following DNS server address and use either one of these DNS'es (*c):

RiiConnect24 (same as Wiimmfi):
Preferred DNS server: 164.132.44.106
Alternate DNS server: 8.8.8.8 (or 1.1.1.1)

Wiimmfi:
Preferred DNS server: 46.4.79.141
Alternate DNS server: Leave it empty.

AltWFC:
Preferred DNS server: 104.131.93.87
Alternate DNS server: Leave it empty.

When you've typed out your DNS, click OK, close everything and open up the USB Connector software.

*a
*b
*c

Spoiler: Patching a rom

1. Unzip all the contents from WfcPatcher1.6.zip.
2. Simply drag the DS game you want to patch onto WfcPatcher.exe. The output file is titled Romname (No SSL).nds.
3. Copy the No SSL rom onto your flashcart.

Spoiler: Connecting to the internet

1. Launch whatever game you want to play and go to the WFC settings.
2. Press Connect to your Nintendo Wi-Fi USB Connector (*a).
3. A connection is trying to be made. On your computer, right-click on your name and press Grant permission to connect (*b).
4. Follow the rest of the instructions on screen. If the USB Connector is found and no errors display, you are connected with a different DNS. Leave the WFC settings and go online!

*a
*b

Spoiler: Troubleshooting

• "The VM software I'm using doesn't want to connect the USB Connector."

Some VM software tend to do that, especially VirtualBox. If that happens, wait for an error message to appear, plug out the USB Connector and plug it back in. Also make sure to not select anything called BUFFALO INC. (formerly MelCo., Inc.) Nintendo Wi-Fi [0001].

• "My DS can't find the USB Connector."

Give it a few tries. Otherwise, disconnect the USB Connector and try again.

• "I got error 52003 / 52103."

Make sure your firewall is disabled for the USB Connector and that the DNS you've chosen is correct.

• "I got error 20100 / 20110 / my game froze."

If you're using a retail cartridge, I can only hope you read the top part of this post, because it won't work. You really have to use a hotspot if you want to use those. If you are using a flashcart, make sure the rom is NoSSL patched.

 

[MaxiBash]

Still got a crash. Maybe it's my wifi, but I'm keeping it this way.

 

[Bagel Le Stinky]

Is there a way to do it without the actual connector?

 

[MaxiBash]

Is there a way to do it without the actual connector?

Nope, otherwise you need to setup a hotspot. iirc if you're running something like Linux, setting up a hotspot nearly isn't as hard.