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Since I built my PC, the network icon in Windows has always displayed as if there were no internet connection, despite there being an active connection to the internet.
I've tried uninstalling the Ethernet device driver and installing the latest version, but that did not help. I've disabled all unused network adapters. I've also tried clearing the tray icon cache using the method detailed here: https://www.sevenforums.com/tutorials/13102-notification-area-icons-reset.html. Unfortunately the issue still persists. I'm not sure what to try next.
I was reading this article: http://blog.superuser.com/2011/05/16/windows-7-network-awareness/ and am thinking the issue might be linked to NCSI in Windows, but am not sure how to troubleshoot if this is the case.
You have started with good research. Have you tried Wireshark to see if your connection to NCSI goes through? Also run
sfc /scannow
for a good measure. – None – 2017-03-04T08:13:34.320I was actually just now able to fix the problem using the workaround here: http://superuser.com/questions/661976/windows-7-shows-red-x-on-network-icon-but-im-connected
I'm not sure if I can close my question without an answer under it, so I answered it myself below.