Marantz NR1710 web interface, volume control?

Hello. I am currently using this receiver. It has a web interface and I can use it for a great deal of things. I seem simply unable to find a volume control in it though. I keep going back to the Audio link in the hope a slider for volume will appear, it doesn’t. I’ve resorted to running OpenHAB and using the home automations to control volume. This requires another something (RPi/NAS/ . . .)running OpenHAB.
Is there a native volume control I’ve just missed?