Generic Android device on fresh reset

Greetings, @CogtheWidget! I hope your week has been treating you well. Thanks so much for taking a moment out of your busy day to leave a post on our community forum. I'm sorry to hear you're having issues with this unknown device, but you have definitely come to the right place for assistance.

Under normal circumstances, you should be able to remove an unwanted device by changing your network name and password, but you already referenced a new WiFi password, so it sounds like you've already tried that. Have you also tried renaming your network temporarily, to see if the device disappears?

I don't think I love the multi band WiFi network because it's causing some devices to show connected 2, 3 times. As an example, if I connect my iphone directly to xFi, then later connect it to an extender, it seems like the xFi shows it twice, once as the resolved name device it connected with directly and then a second connection same ip but some decide id that has a Mac address seemingly assigned by my extender. Unsure if that was what was going on or what

Hello @CogtheWidget! Some Wireless Gateways support a feature known as Device Discovery or Universal Plug 'n' Play (UPnP), which allows UPnP-capable devices on your home network to automatically discover each other's presence and begin sharing data. This feature creates an easier home networking setup experience than individually configuring these devices to talk to each other over your Wi-Fi network. Common uses for device discovery include setting up shared computers or printers on your network. 

To configure device discovery, connect to your Wi-Fi network and access 10.0.0.1 from a web browser.
Once logged into the Admin Tool, navigate to Advanced > Device Discovery.
You may see UPnP default to being enabled, which automatically opens ports for appropriate applications and services for UPnP-capable devices on your network. You have the ability to disable this in the Admin Tool.

If you would like to leave UPnP enabled, you can modify the Advertisement Period, which is how often the Wireless Gateway broadcasts its UPnP information to devices on the network, and the Time To Live, which measures how far (in hops away from your gateway) the UPnP information will be broadcasted before advertisement stops.

You also have the ability to enable Zero Config, which is a discovery protocol that allows UPnP-capable devices to connect automatically.
Advanced > Device Discovery screen

After adjusting any of these settings, remember to click Save to execute your configuration. Let us know if this helps with the way your network is discovering your devices.