RESOLVED It looks like this issue was fixed at some point in the last 12 hours or so: As a test, I tried installing mods from inside Factorio again, and several that I had issues with the previous day were installing fine now. Whatever was breaking the transfer from the server is resolved now (noth...

Quick followup note: I did a fresh install of Factorio (removed the AppData/Factorio folder to do a completely fresh reinstall); still continuing to see the same mod download problem.

RESOLVED as of 11:50AM JST : It looks like this issue was fixed at some point in the last 12 hours or so: As a test, I tried installing mods from inside Factorio again, and several that I had issues with the previous day were installing fine now. Whatever was breaking the transfer from the server i...