RT-N66U Upgrade to Windows 10

I have a small home network operated through an RT-N66U. Three computers are connected via Internet and one by Wi-Fi. Internet connection is via a Billion modem with wired connection. I also have three phones/tablets connected by WiFi. The 4 computers were previously operating Windows 7 (2) and Windows 8.1(2). I have recently upgraded all 4 to Windows 10. Previously the network had set up with no problems at all basically using default settings.

After upgrading to Windows 10 the three...

RT-N66U Upgrade to Windows 10