Package Manager can't establish connection

As I'm reading the forum threads about the unity packages, I can tell that I'm not the only one who's having this problem. I really need help now regarding this issue, as I've done some of the recommended fixes myself but nothing worked so far.

Some needed info from the issue are already on the attached files (and the ff images):







So far upon posting this, I already have:

• Set the environment variables
• Added (and re-added) 'Unity Editor' in the Inbound Rule of the Windows Firewall
• Added an inbound rule for the package manager itself
• Uninstalled previous versions of Unity (and 2020 ver) and reinstalled
• Uninstalled and reinstalled Hub to latest version
• Tried running via Unity 2020 shortcut itself (although the project opened only once when I tried)

I'm running on Windows 8.1. I have the Hub installed on a different 'storage' (I have two storage, the OS (C) and the DATA (D) but they share the same hard disk drive, just separated storage space for each). I had a previous version of Unity installed before, and had installed the 2019 with it but I haven't used it until I had a project (that was built in that prev ver.) that I want to finish at that ver. and then planned to switch to a newer version but the package manager issue then started happening (although it did run once).