Got a smart TV, Blu-Ray player, Roku streaming device, thermostat, Ring doorbell, security camera, tablet, smart speakers, laptop, or smart phone? As bassfisher noted, it could be a number of devices in your home connecting,
or trying to connect.
Then make sure to change your login user name and password and then do a factory reset on your modem/router.
Ummm, I'm not seeing a reason to reset the router at this point. It certainly will not hurt but I note if you reset your router
after you change your log-in credentials, your new password will no longer work because those required credentials in your router will be reset back to the factory defaults.
You may have to run around the house and power off AND UNPLUG from the wall (to ensure not in standby mode) all your devices. Then, one-at-a-time, connect again while checking your connected devices.
And speaking of "connected devices", you should be looking in your router's Admin menu for these to see what is actually connected (not just "trying to" connect) to your network. There should be a menu page showing each device currently connected to your network. In my Netgear, they are listed under the Tab called "Attached Devices". Mine shows how it is connected, (wired, 5GHz wifi or 2.4GHz wifi), the device name (which I can edit to say, for example, "My PC" or "My Laptop"), the assigned IP address, and the network adapter's MAC address.
If you cannot determine which device belongs to that 192.168.0.101 IP address, then for sure, I would change wifi passphrase in the router. This of course, will force you to set a new passphrase in all your authorized wifi connected devices - in effect, resetting your wifi network. This will make sure the next door neighbor whizkid currently stealing your wifi and Internet access is kicked out.
The only way an unauthorized device could be connected via Ethernet (wired) would be to physically connect a Ethernet cable to your router or switch. And hopefully, you would notice a strange cable if that is happening.
Note also, all networkable devices should have a sticker on them some where with the MAC address listed.
Some devices, like my Roku streaming devices, supports both Ethernet and wifi. So it has two network adapters, two MAC addresses and can, if I let it, connect both ways with two different IP addresses.
You might even try entering 192.168.0.101 in your browser address bar and see where it goes. You might just end up at your Modem's admin menu log in screen.
Or HID - typically your mouse and keyboard.
