Hi,
This is probably due to network configuration issue (proxy).
Make sure that any sort of antivirus or firewall installed on the system are not blocking anything in the MATLAB installation directory.
Please also confirm that there is no ip protection software (eg Symantec Data Loss Prevention) blocking communication.
If the network setting on your machine uses HTTP proxy, modify the network configuration to add an HTTP proxy exception.
In Windows, you can do this by :
Going to Control Panel -> Network settings -> Internet Options -> Connections -> LAN Settings -> turned ON "Bypass proxy server for local addresses" with "Use a proxy server for your LAN".
If a proxy server is used you could also check if it might be not properly set in MATLAB and adapt the settings.
To do so: Please enter the proxy server details in the MATLAB Preferences that can be opened from the Home Tab in the MATLAB toolbar
Preferences -> Web section
You can also refer to a similar question here : https://www.mathworks.com/matlabcentral/answers/325298-failure-to-start-simulink
