Had the same problem with a Dell 17r 7720se, Intel Centrino N-2230 wifi card with 15.9.2.1 driver. The false no connection exclamation point displayed on wifi icon in task bar. I too had a working wifi connection showing in internet connections but the exclamation point would remain until IE was opened.
Frederic_MUC's solution worked. But I have 3 boxes: Unchecked all three - "Enable Intel WiFi HotSpot Assistant" and "Automatically connect to free wifi hotspots" and "Automatically connect to paid (subscription) wifi hotspots" in Intel PROSet/Wireless Tools /Intel Wifi Hotspot Assistant /settings. I did not uninstall anything. Just rebooted and the nasty little exclamation point icon disappears in 2 seconds after startup when wifi connects.