iPad volume max, uncontrollable with TV via HDMI
Volume at max when connecting IPad to Samsung TV via HDMI and cannot control volume up/down with either IPad or TV remote
When using HDMI, the audio volume from the source device (in this case your iPad) is fixed; volume control is achieved using controls available on the connected monitor, TV or audio device.
As described, your issue is with your TV not being able to control the audio volume from the HDMI source.