When I use the Net Analyzer android app to look at WiFi signals, I see on channel 1 of the 2.4Ghz band a signal with a hidden SSID and a mac address of ff:ff:ff:ff:ff:ff. The strength shows -86dBm from a -100dBm floor and is much stronger than mine or any of the neighbouring WiFi signals compared to me sitting 2m from my own router with a strength of -45dBm.
On NetGear WiFi Analytics android app I see it with a strength of 0dBm
The signal is not encrypted and signal strength doesn't change.
I have turned my devices off, so I know it is not from me.
Would you say this is faulty equipment or a jamming signal on the channel one frequency?
You may misunderstand the relative signal strength values due to the negative signs (-).
-45dBm is much stronger than -86dBm. https://en.wikipedia.org/wiki/DBm
With a reported strength of 0dBm that does not change, it may be from the NetGear WiFi Analytics android app itself. Perhaps sending out some discovery packets via broadcast (ff:ff:ff:ff:ff:ff) to evoke a response from idle wifi devices. I don't have any experience with that app though.
The "Network Analyzer" android app measures up from a base of -100db. In other words is it -14dBm the signal (-100--86) the closest signal with me 2m from the router is -44 (-100--56)
The "Netgear Network Status" android app shows it as 0dbm when you scan for WiFi networks.
I suppose the simple test is, if i go down the road and scan and it is still 0, it is coming from the phone itself
As @spence said, as dBm levels go more negative, that means a weaker signal. The "noise" number of -100 is nominally the weakest detectable signal. Otherwise the "noise" number doesn't mean anything.
A signal in the -80s is usually coming from a few houses away, so as you said move around outside and see where it becomes stronger (moving in the direction toward 0 dBm.)
These analyzer apps just call the phone's core wifi API and present what was returned, so trying an entirely different phone and / or OS version would also help show if it is a false report.