title: Jupyter lab NetworkError running on WSL2
body: <p>I am running Jupyter lab on my WSL2 Ubuntu and accessing it in Firefox on my Win10 PC. They are running on the same machine, so there should be no &quot;Network&quot; involved. I am running it as <code>jupyter lab --no-browser</code>. The Server launches just fine in the terminal:</p>
  <pre><code>[I 11:17:40.843 LabApp] [jupyter_nbextensions_configurator] enabled 0.4.1
  [I 11:17:40.885 LabApp] JupyterLab extension loaded from /home/muthur/anaconda3/lib/python3.8/site-packages/jupyterlab  
  [I 11:17:40.886 LabApp] JupyterLab application directory is /home/muthur/anaconda3/share/jupyter/lab                    
  [I 11:17:40.888 LabApp] Serving notebooks from local directory: /home/muthur                                            
  [I 11:17:40.888 LabApp] Jupyter Notebook 6.2.0 is running at:                                                           
  [I 11:17:40.888 LabApp] http://localhost:8888/?token=...                                                                
  [I 11:17:40.888 LabApp]  or http://127.0.0.1:8888/?token=...                                                            
  [I 11:17:40.888 LabApp] Use Control-C to stop this server and shut down all kernels (twice to skip confirmation).
  </code></pre>
  <p>But when I start it in my browser, I first get &quot;Server Connection Error: A connection to the Jupyter server could not be established. JupyterLab will continue trying to reconnect. Check your network connection or Jupyter server configuration.&quot;, which in the F12 console is due to <code>Uncaught (in promise) TypeError: NetworkError when attempting to fetch resource.</code> Reloading the tab or opening it in a new one gives me the Firefox &quot;Connection failed&quot; error page, saying that it cannot establish a connection to <code>127.0.0.1:8888</code></p>
  <p>I have been using this setup for the past 2-3 months without issue. Any idea why this crops up now, and how to solve it?</p>