From bleepingcomputer.com
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.