I have been going nuts with a yellow triangle over the network connection icon in the system tray of my Windows 8.1 Asus T100chi. The reason this was so frustrating was that my network connections all seemed OK with one exception. So, browsing using IE worked, the Windows Store worked, Outlook email worked. Office 365 Personal worked except that it always had hiccups if the document I worked on was on OneDrive.
I use my T100chi at the office and at home. At the office, it is connected to my firm's Ethernet using an Asus Varidrive. The Asus Varidrive is a slim silver box roughly the size of a DVD case that has a DVD burner, HDMI and VGA ports, three USB 3.0 ports and an Ethernet port. It connects to the T100chi via the USB 3.0 socket on the top of the left hand side of the T100chi. Although it appears physically as one box, in terms of the devices seen by the Windows OS it is actually a USB hub with multiple devices hanging off of it, those devices being a Displaylink USB to video card, an ASIX USB to Ethernet card and (I think) a Genesys mass storage controller (do not quote me). I spent a lot of time exploring the possibility that it was a problem with the Varidrive. I tried using the micro HDMI port on the T100chi for the video to see if freeing up USB bandwidth would help the Ethernet. It did not.
I tried the usual solutions suggested on the web: flush the DNS cache; boot in safe mode with networking; disable the other network card (Broadcom WiFi). None of those made any difference.
Finally, I have worked out the problem. My firm has a proxy server. At home, I do not have a proxy server. Also, my firm has a set of standard mapped network drives. At home, I have a different set of mapped network drives. I have two sets of three batch files that I ran just after booting up at home or at the office. The batch files set (1) the proxy settings for IE (on at work, off at home) (2) the proxy settings for winhttp (on at work; off at home) (3) the mapped network drives. (Yes, I could merge these into one batch file for each of home and work but as it now turns out it is good to have them separate when it becomes necessary to troubleshoot).
I have been using these six batch files for well over a year. Before my T100chi, I had its predecessor, the T100TA. They all worked flawlessly.
When I changed over to the T100chi I copied them over to the T100chi and just kept on using them and assumed they were working fine (d'oh). It looked like they were working fine because, for example, I could browse Windows Store. So, when I looked at the troubleshooting for Office 365 at this link https://support.microsoft.com/en-us/kb/2745026 initially I just skipped over Step 1. Wrong! It turns out that I need to run my batch file for the winhttp step as administrator. I cannot recall that I ever used to do that. I have a feeling that there is some queer quirk in the way that I had the T100TA set up versus the T100chi but I cannot put my finger on it (see further below). Anyway, the bottom line of this rambling is that after I had run the following command as administrator the yellow triangle went away:
%comspec% /c netsh winhttp set proxy %proxyserverandport% >> %logfile%
The %proxyserverandport% variable is set up earlier in the batch file but it is basically along the lines of 192.168.1.123:8080. You can delete the section from >> on if you do not want to log the output but if you do want to log, you need to set the logfile variable or hard code in the file path for the log.
Once that was run, all my OneDrive and Office 365 issues appear to have sorted themselves too.
As a kind of postscript, you might be interested in the different set ups of the T100TA vs T100chi that could have contributed. When I set up the T100TA initially, I did so using my Microsoft live account. Later, one of my firm IT guys joined the T100TA to the firm domain. I then used solely the Windows 8.1 built-in setting sync functions to get my domain user account looking the same (e.g. log on pictures, desktop wallpaper). With my T100chi, I set it up much the same way except that after the IT guy had added my PC to the domain, I used User Profile Wizard 3.9 from ForensIT (which I wholeheartedly recommend) to transfer my profile.
