How to change AEM Startup Parameters after Setting it up as a Windows Service

Adobe official documentation for setting up AEM on Windows Server 2016 to auto-start on reboots is available here. It uses Apache Commons Daemon Service Runner prunsrv_amd64.exe for this. AEM ships with it (available at \crx-quickstart\opt\helpers).

Even though the documentation tells you that any changes you make in instsrv.bat will not take effect until you re-install the Windows service, this is not true. You can also edit the registry key (as Administrator) Computer\HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Apache Software Foundation\Procrun 2.0\cq5\Parameters\Java and re-start the service for the changes to take effect. For example, changing the heap size, or enabling GC logging.

Note that you can change the TCP port (-p argument) as well as the local network interfaces (-a argument) AEM LISTENs on by editing the registry key (as Administrator) HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Apache Software Foundation\Procrun 2.0\cq5\Parameters\Start\Params

Example: -p 4503 -a 0.0.0.0