NetBeans Keeps Its Internet Proxy in General Options
Set the IDE’s manual HTTP proxy under General options, then distinguish IDE downloads from networking in the application being run.
For NetBeans’ own Internet access, open Tools → Options → General. Select the manual HTTP proxy option, enter the hostname and port separately, and apply the changes.
For http://proxy.example:8080, enter proxy.example as the host and 8080 as the port. For permitted public update-center access, the HTTP proxy list provides candidate host and port values.
The panel also offers direct access and system proxy settings. Choose the intended mode; entering a host while “No Proxy” remains active does not enable the manual route.
This controls IDE requests such as update-center access. For a failure in the Java application launched by NetBeans, inspect that application’s JVM or HTTP-client settings.