java.net.NoRouteToHostException: No route to host (Host unreachable)

This exception is thrown when the network is unable to establish a connection between two hosts. This can happen when the destination host is not reachable, or if there is a problem with the network configuration.

There are several possible reasons for this exception, including:

1. Network failure: If there is a problem with the network, such as a broken cable or a router failure, the connection may be lost.

2. Firewall or security restrictions: Some firewalls or security software may block connections to certain hosts or ports, which can cause this exception.

3. Incorrect IP address or hostname: If the IP address or hostname entered is incorrect, the connection will not be able to be established.

4. Server is down or not running: If the server is not running or is down, the connection will not be able to be established.

To troubleshoot this issue, you can try the following:

1. Check the network connection: Ensure that the network connection is working correctly.

2. Check the firewall settings: Check the firewall settings to ensure that they are not blocking the connection.

3. Check the IP address or hostname: Verify that the IP address or hostname entered is correct.

4. Check the server status: Check that the server is running and responding to requests.

If none of these solutions work, you may need to contact your network administrator or IT department for further assistance.