Running TestNG test hangs on "Instantiating tests..." stage when VPN is enabled

Problem

Starting TestNG test execution hangs on the "Instantiating Tests..." phase if VPN is enabled.

Log idea.log (Help | Show Log in Explorer/Finder) containing Socket closed errors:

INFO - #c.i.e.t.SearchForTestsTask - Socket closed
java.net.SocketException: Socket closed
	at java.base/sun.nio.ch.NioSocketImpl.endAccept(NioSocketImpl.java:694)
	at java.base/sun.nio.ch.NioSocketImpl.accept(NioSocketImpl.java:767)
	at java.base/java.net.ServerSocket.implAccept(ServerSocket.java:675)
	at java.base/java.net.ServerSocket.platformImplAccept(ServerSocket.java:641)
	at java.base/java.net.ServerSocket.implAccept(ServerSocket.java:617)
	at java.base/java.net.ServerSocket.implAccept(ServerSocket.java:574)
	at java.base/java.net.ServerSocket.accept(ServerSocket.java:532)
	at com.intellij.execution.testframework.SearchForTestsTask.run(SearchForTestsTask.java:112)
	at com.intellij.openapi.progress.impl.CoreProgressManager.startTask(CoreProgressManager.java:477)
	at com.intellij.openapi.progress.impl.ProgressManagerImpl.startTask(ProgressManagerImpl.java:133)
	at com.intellij.openapi.progress.impl.CoreProgressManager.lambda$runProcessWithProgressAsynchronously$6(CoreProgressManager.java:528)
	at com.intellij.openapi.progress.impl.ProgressRunner.lambda$submit$4(ProgressRunner.java:250)
	at com.intellij.openapi.progress.ProgressManager.lambda$runProcess$0(ProgressManager.java:100)
	at com.intellij.openapi.progress.impl.CoreProgressManager.lambda$runProcess$1(CoreProgressManager.java:221)
	at com.intellij.platform.diagnostic.telemetry.helpers.TraceKt.use(trace.kt:46)

Resolution

VPN service should be configured to bypass all traffic from IDE/Java or disabled.