Error Code 0x80070643 or 0x643 error code is common for all the Windows Operating systems when you try to install the updates. It usually appears when Windows 10 or Windows 7 update system is broken or there is network related glitches.
Usual causes for this issue 0x80070643 or 0x643 error are communication failure over the internet with Microsoft update servers.
Firstly, I will suggest you to do Windows Troubleshoot for windows update error 0x80070643.
Disable the proxy internet connection and try again to install the update.