Switch off (or put into aeroplane mode) any iOS14 devices you may have then enter http://192.168.1.254/my_network.htm into a browser and click on the Remove button alongside the device, does it come straight back up when you reconnect the iOS device?
Thanks for that Les. I did what you suggested and both my iPad and iPhone were both added to list when I restarted them.
As I thought, it's nothing to be concerned about.
See this link for more detail: https://support.apple.com/en-gb/HT211227