Microsoft has acknowldeged a Windows 10 internet connectivity issue caused by the update KB4535996. In a new entry on the Windows 10 release information page for update 1909, Microsoft admits that Windows 10 OS Build 18363.693 aka update KB4535996 may be resulting in limited or no internet connection status on devices using a manual or auto-configured proxy.
This issue is more prevalent when using a VPN with devices using a manual or auto-configured proxy. This issue also affects a number of apps like Microsoft Teams, Microsoft Office, Office365, Outlook and more.
Devices using a proxy might show limited or no internet connection status
Devices using a manual or auto-configured proxy, especially with a virtual private network (VPN), might show limited or no internet connection status in the Network Connectivity Status Indicator (NCSI) in the notification area.  This might happen when connected or disconnected to a VPN or after changing state between the two. Devices with this issue, might also have issues reaching the internet using applications that use WinHTTP or WinInet. Examples of apps that might be affected on devices in this state are as follows but not limited to Microsoft Teams, Microsoft Office, Office365, Outlook, Internet Explorer 11, and some version of Microsoft Edge.
The issue affects all Windows 10 versions from version 1909 to version 1709.