Windows 10 Pro, Dell Optiplex computer, an RT-AC66-U, 2 RT-AC68U's, and just bought an RT-AC86U. When connecting to the internet, with an Android cell phone, through any of them I often get "Network cable unplugged" error message and cannot access any webpages. I have tried changing NIC adapter Speed &Duplex settings to no avail. However; I can ping any site on the internet and the status page of all the routers show Internet Status is connected with a WAN IP address. When I turn off Windows Defender I can connect to web pages over the internet. I have another RT-AC68U connected to a different Android Cell Phone and different computer running Win8.1 that I'm using to connect to the internet and send this message. I have checked all of the settings on the other routers against the settings on this router to see if there is something different, if there is I haven't spotted it yet. I can tether the Android direct to the Win10 Pro with USB cable and get to the internet with Windows Defender turned on. I need to be able to use the router to connect to security cameras but really don't want to run with Windows Defender turned off perpetually. Have searched internet but have not found what setting I need to fix in Windows Inbound or Outbound Rules to fix this issue. THANKS for any suggestions!