Symptoms
If you are trying to update to Windows 10, version 2004, you might encounter an update compatibility hold and receive the message, "This PC can't upgrade to Windows 10. Your PC isn't supported yet on this version of Windows 10. No action is needed. Windows Update will offer this version of Windows 10 automatically once the issue has been resolved."
Cause
An issue has been found with certain wireless wide area network (WWAN) LTE modems and Windows 10, version 2004. After installing Windows 10, version 2004 on Windows 10 devices with an affected WWAN LTE modem, you might not be able to reach the internet using that WWAN LTE modem.
To safeguard your update experience, we have applied a compatibility hold on these devices from installing or being offered Windows 10, version 2004.
Next steps
This issue was resolved in KB4568831. The safeguard hold has been removed as of August 13, 2020. Please note, if there are no other safeguards that affect your device, it can take up to 48 hours before the update to Windows 10, version 2004 is offered.