Office 365 cloud features do not work when using a privacy VPN

I reiterate that my own experience has been as follows running Office 365 under Windows 7:

• NordVPN would not allow Outlook under Office 365 to work at all, period, even after trying all the fixes with default gateway etc, and senior tech support at NordVPN finally cited threads to me on forums showing that for many users it's simply not fixable (I didn't try OneDrive or OneNote)
• HotSpot Shield has worked with Outlook and all of Office 365 flawlessly, and overall it's a more efficient VPN than anything else I've tried
• CyberGhost has also worked perfectly fine with all of Office 365 (settings: OpenVPN, TCP, no random ports, DNS leak protection, disable IPv6)

I've also tried PIA with only spotty success, and ExpressVPN which seemed okay but failed once so I dropped it (and I didn't like it in general).

I have no affiliation whatsoever with any of these companies. I'm just a business end-user.

Success!  Thanks for your contribution!

After more than a year of struggling with this issue and striking out with both Microsoft Office and OneDrive support techs...I was relieved to discover Mac Wheeler's resolution to this issue

(https://www.macwheeler.com/windows-10-office-365-cannot-connect-over-openvpn-fixed/).   Assigning a default gateway address to the IPV4 protocol works like a charm!  I used 198.162.1.1 and it immediately resolved the issue.

I have wasted many hours of time with MS Office support techs who were absolutely clueless.  OneDrive support is not reachable by phone and they too are clueless; point the finger at their Office support colleagues.   It is amazing to me that the Sr. Software Engineer I last spoke with at Microsoft was completely unaware of the issue and any solution for it.   It causes one to ponder how internally fragmented the MS organization might be.  Frankly, it ought to be a bit embarrassing that Microsoft has allowed this issue to cause so many users so many problems for so many years.

By the way, Office365/OneDrive connectivity through a VPN has never been an issue for iOS MacBook.

Buy a MacBook.  OneDrive connectivity with Office365 is not an issue with iOS.

I've tried every fix posted. While I had some success with several, none were completely satisfying. For example, saving to OneDrive would work, but I'd have to select a Canadian server to access Amazon. I realized that I was spending time troubleshooting and trying rather then working. I ended up switching away from NordVPN to HotSpot Shield Premium (I don't have any connection to them other  than being a customer) and am very satisfied. It works. I don't think about it. And I work more efficiently. HotSpot offers a freemium service. After testing I chose Premium and "ate" my NordVPN fee. I know that's not for everyone and I felt like I had wasted money, but the gains in peace of mind and performance have been worth it.

Yes, this is kind of my concern too - I'm not an expert, and don't really understand what adding the gateway actually does in practice, and whether, as you say, it's negating the point of having a VPN, or has some other unintended security consequence etc.

Any advice would be welcome, thanks!