OpenWRT luci integration reporting "Method not found"

[dvenza]

The problem

I added in my configuration.yaml the following section, according to the docs for the OpenWRT luci integration:

device_tracker:
  - platform: luci
    host: 192.168.1.1
    username: root
    password:

After restarting home assistant I get the following in the logs:

Traceback (most recent call last):
  File "/usr/src/homeassistant/homeassistant/components/device_tracker/legacy.py", line 339, in async_device_tracker_scan
    found_devices = await scanner.async_scan_devices()
  File "/usr/src/homeassistant/homeassistant/components/device_tracker/legacy.py", line 806, in async_scan_devices
    return await self.hass.async_add_executor_job(self.scan_devices)
  File "/usr/local/lib/python3.8/concurrent/futures/thread.py", line 57, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/usr/src/homeassistant/homeassistant/components/luci/device_tracker.py", line 63, in scan_devices
    self._update_info()
  File "/usr/src/homeassistant/homeassistant/components/luci/device_tracker.py", line 91, in _update_info
    result = self.router.get_all_connected_devices(only_reachable=True)
  File "/usr/local/lib/python3.8/site-packages/openwrt_luci_rpc/__init__.py", line 42, in get_all_connected_devices
    return self.router.get_all_connected_devices(
  File "/usr/local/lib/python3.8/site-packages/openwrt_luci_rpc/openwrt_luci_rpc.py", line 161, in get_all_connected_devices
    arp_result = self._call_json_rpc(*self.arp_call)
  File "/usr/local/lib/python3.8/site-packages/openwrt_luci_rpc/openwrt_luci_rpc.py", line 229, in _call_json_rpc
    raise LuciRpcMethodNotFoundError(
openwrt_luci_rpc.exceptions.LuciRpcMethodNotFoundError: ("method: '%s' returned an error '%s' (code: '%s).", 'net.arptable', 'Method not found.', -32601)

My OpenWRT router is a Turring Omnia, the luci-mod-rpc is installed at version git-21.062.76689-a607f9c-1 (the default from the official turris repository).

What is version of Home Assistant Core has the issue?

core-2021.5.4

What was the last working version of Home Assistant Core?

No response

What type of installation are you running?

Home Assistant Container

Integration causing the issue

OpenWRT luci

Link to integration documentation on our website

https://www.home-assistant.io/integrations/luci/