MicrosoftSAPacker I am not sure if this is still the case, has been a while since I have tested it. But next Patchday for customers will come and there are new updates to import (of Importance) e.g. Intel Microcode. While one can import Updates while using a WSUS MMC on a remote computer, it still demands to set the default browser to IE (temporarily please).
Please try this. Set your default browser to IE, WSUS MMC > Import Updates
Can you please check if the TLS settings in IE (internet options are set to disable TLS 1.0 / TLS 1.1, not yet the default and only enable TLS 1.2) thanks for reporting back if this works for you.
If you like, you can also use PowerShell. here is a german blogpost from Wolfgang Sommergut, a very good expert. The new Edge Browser should help you to translate this live from german into your language.
https://www.windowspro.de/wolfgang-sommergut/updates-manuell-wsus-importieren-ie-powershell
