After starting my Windows 8.1 laptop, if I go to the Control Panel\Network and Internet\View Network Computers and Devices, a device is listed that is not on my network. It is listed as either a Ralink wireless client Model # RT286U or a full_ariel Model KFARWI and if I right click on the device and view the properties the Model #, Name, and MAC Address are shown. I checked the Device Manager and it was not listed in the Device Manager. Also, my router did not show it as an attached device. I have Win 8.1 laptop, a Win 7 laptop, an iphone, android phone, ipad, WD NAS, and HP wireless printer connected to a Netgear AC wireless router with MAC address filtering enabled. When I log into the router I have never seen either device mentioned above listed on the router list of attached devices nor do any of the devices I have on my network have the MAC address listed for either device. After a short period of time the device disappears. I have set up my network as a private network. My concerns are: Are the devices a security issue and can they access my network? How come my computer detects them? The devices do not list either a work group or a network location so am I correct in assuming the devices are not connecting through my router? Is there anything I can do to prevent it from being detected?