Starting 500 LG's may be challenging especially at the network level. By default, 15 LG's will receive your project at the same time. Depending on your available bandwidth on your network, it may not work and it will lead to such error.
The number of LG's initialized at the same time can be customized in the <install_dir>\conf\controller.properties file under [Runtime] section. It's the option engines.init.pool.size=15
Have you ever been able to start a test with less LG's?
