udp connection fails when wifi is disconnected

I am trying to create a udp connection to the local host, if I am connected to wifi, it is successful but if I disconnect from the wifi, I get the errror below. How is the wifi connection affecting this?

>> u = matlabshared.network.internal.UDP( ...
      'RemoteHost','127.0.0.1', ...
      'RemotePort',14550, ...
      'LocalPort',14570, ...
      'EnablePortSharing',true);
>> u.connect

Cannot create a communication link with the remote server. Please check the input arguments(ADDRESS and PORT) and make sure
the server is running.
Additional Information: resolve: Host not found (authoritative) [asio.netdb:1]

[Walter Roberson]

Good question. The existance of the wifi network or not, should not affect the local network 127.0.0.1

[KnightHawk]

This appears to only happen in Ubuntu (specifically 22.04), windows doesn't have a problem.

[Ishaan]

Hey,

I noticed you are using a function that I couldn't find in the official MATLAB documentation. However, there's a function called "udpport" that provides similar functionality for UDP connections. I have tried it on my Windows machine, and it works well, even when I'm not connected to Wi-Fi.

Here is an example showcasing how you can use it.

>> u = udpport("datagram", "LocalPort", 14570, "EnablePortSharing", true);

>> write(u, data, "uint8", "127.0.0.1", 14550);

>> dataReceived = read(u, numBytes, "uint8");

For more information on "udpport", please refer to the following documentation link:

https://www.mathworks.com/help/releases/r2023b/instrument/udpport.html

Answer 1

[Abhiram]

Hi @KnightHawk,

It seems that some UDP features are unable to resolve local IP addresses when the machine is offline on some Linux distributions.

This is a known issue and has been reported as a bug by MathWorks Support as specified in the given Bug Reports page:

https://www.mathworks.com/support/bugreports/3569310