RS500 connected devices list doesn't match nighthawk and home assistant apps

It might be entertaining to see if this Python program works with your RS500:

# get_dev.py  Python program to retrieve attached devices list from Netgear router
#
# Requires Python library "Requests".  See https://pypi.org/project/requests/ for installation instructions
#
# requests==2.25.1
import requests
from requests.auth import HTTPBasicAuth
# urllib3==1.26.3
import urllib3
import json

# Define the IP of the router, admin user name (typically "admin"), and the admin password.
router_ip = '192.168.1.1'
admin_user = "admin"
admin_password = "Enter admin password here"

def get_connected_devices(url, admin, passwd):
	r = requests.get(url, auth=HTTPBasicAuth(admin, passwd), verify=False)
	devices = r.text.splitlines()[1][7:]
	return r.status_code, devices

if __name__ == '__main__':
	print('STATUS: Starting execution.')
	urllib3.disable_warnings()
	# Preparing to call get_connected_devices
	# IP address for the Orbi router

	# URL to query connected devices
	router_url = 'https://'+router_ip+'/DEV_device_info.htm'
	http_response, devices_text = get_connected_devices(router_url, admin_user, admin_password)
	print("HTTP response ",http_response)
	# The Netgear router sometimes does not honor the request and returns 401
	# just try again and will succeed eventually
	if http_response != 200 :
		if http_response == 401 :
				print ("This happens sometimes. Please run program again")
				exit
		else :
			print(f'ERROR: Failed to retrieve devices from router: response code {http_response}.')
			print('ERROR: Verify settings and hardware.')
	else:
		print('SUCCESS: Devices connected to router:')
		print(json.dumps(json.loads(devices_text), sort_keys=True, indent=4))
	print('STATUS: Finished execution.')