In the latter versions of Java you need to specify host. Otherwise it'll be "loopback": only connection from the same host would be possible. If Tomcat is started as Windows service, then change Java options: -Xdebug -Xrunjdwp:transport=dt_socket,address=*:9043,server=y,suspend=n What will happen if to use address=9043 with port only? Open Windows Resource Monitor -> Network tab -> Listening Ports: But when we change it to address=*:9043, Address becomes IPv4 unspecified. How to check from the machine with IDE. You can use the following PowerShell command: Test-NetConnection host.address -Port 9043 The output in case of address=9043 is the following: PS C:\Users\username> Test-NetConnection host.address -Port 9043 WARNING: TCP connect to (host.ip : 9043) failed ComputerName : host.address RemoteAddress : host.ip RemotePort ...