There was a firmware update last week and it may be that some of your settings have somehow changed - try this which I found helpful:
If your Marantz Cinema 70s is no longer waking up or turning on automatically when you start playing music from Roon, it is almost always caused by the receiver’s Network Control setting reverting to its default power-saving mode. When this happens, the receiver completely shuts down its network card during standby to save electricity, making it invisible to Roon. [1, 2]
- Fix the Network Standby Setting
To fix this, you must change the network configuration so the network interface stays powered on when the receiver is turned off: [1, 2]
- Grab your Marantz remote and press the Setup button.
- Navigate to Network > Network Control.
- Change the setting from Off In Standby to Always On. [1, 2, 3]
Note: This allows the Roon Server to ping and wake up your Cinema 70s over your home network, though it will slightly increase standby power consumption. [1, 2]
- Verify the Roon Ready Toggle
Recent Marantz firmware updates introduced a dedicated toggle that can occasionally get switched off during a system update. [1]
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Open the Marantz Setup menu.
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Select Network > Roon Ready.
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Clear Network Communication “Hiccups”
If the settings above are correct but the issue persists, the Roon Core and the Marantz handshake may be out of sync. Try a sequential network power cycle: [1]
- Completely power down your Marantz Cinema 70s and unplug its power cable from the wall.
- Reboot your Roon Server/Core device.
- Plug the Marantz back into power and turn it on.
- Open your Roon App > Settings > Audio to verify if the Marantz Cinema 70s appears normally as a “Roon Ready” zone. [1, 2, 4, 5]
If the receiver still does not wake up, let me know if your Marantz is connected via Wi-Fi or Ethernet, and if it responds to the HEOS app while turned off.