You cannot connect to the same shared MATLAB session twice. This is because the "StartMATLAB" function returns a "unique_ptr" object in C#, which disposes of the object in the background once the pointer has been released either by assigning it a null value or by terminating the engine client.
It is possible that the "FindMATLAB" function will still return the same shared MATLAB session after the pointer has been released, but trying to connect to it with the "ConnectMATLAB" function will cause an error or crash the application. This is because the session of MATLAB is closing in the background.
You can open a shared MATLAB session in the command window with the command:
matlab -r matlab.engine.shareEngine
The session pointer obtained by the "FindMATLAB" and "ConnectMATLAB" workflow can now be disposed and added again. The overall workflow here would be to either manually open the shared session of MATLAB from the command line or automate it with a .bat script and call it with the system calls in C#.
For more information regarding opening a shared MATLAB session in the command window, refer to this documentation: https://www.mathworks.com/help/matlab/matlab_external/connect-to-existing-net-shared-session.html
For more information regarding disposing a MATLAB session, refer to this documentation: https://www.mathworks.com/help/matlab/apiref/mathworks.matlab.engine.matlabengine.html#mw_20c55eca-e420-4f2e-89b1-c1d339ebe4ab:~:text=Hello%2C%20shared%20MATLAB.%22)%3B%0A%20%20%20%20%7D%0A%7D-,Dispose,-static%20void%20Dispose
