Microsoft says that computers with a wireless wide area network (WWAN) LTE modem may lose Internet connectivity after installing the Windows 10 KB4556799 cumulative update.

WWAN modems allow mobile devices, such as laptops, to connect to a cellular network and use the Internet while traveling.

These modems are either integrated into laptops or can be purchased in the form of mini PCI-E adapters or USB adapters.

Windows 10 incorrectly states your connected to the Internet

In an update to the Windows 10 KB4556799 support bulletin, Microsoft states that Windows 10 devices using WWAN LTE modems may not be able