About TLS and ciphers, is this a system that underwent PCI lockdown where you suspected that?
Windows Ciphers causing backup to fail to onedrive. There are directions for trying to select TLS.
PCI has also been known to disable weak ciphers, and I’d suspect that an older system has some.
I posted an example of using Wireshark to get a nice view of the cipher situation, but I will say that
the problem with this theory is that a certificate failure seems like it should stop list, not just upload.
The Internet Explorer failure is more thorough. Duplicati’s partially working status is a little stranger.
The way this topic began, there were some, so upload was working then. What may have changed?
Do you recall any file sizes or dates? For upload testing, I would suggest starting with very small file.
Upload or replace the contents of a DriveItem says beyond 4 MB is done differently. I haven’t tested.
Can BackendTool download (get) a file if you manage to point to an existing one or get one in there?
What sort of OneDrive is this? That’s kind of a brand name, with different packaging and technology.
Is it paid up and with enough free space? Not having that might get you in an uploads-blocked status.
How locked down is this system and its environment? Can you install other browsers for some tests?
Corporate networks, antivirus programs, and data exfiltration prevention might interfere with requests.
You can get a clue if something is in the middle by looking at a web site’s certificate to read its issuer.