Recently I've noticed that downloading pictures from Danbooru doesn't work with download managers (IDM to be specific). Attempting to download a file only produces a 403 forbidden error message. Downloading with the browser still works, though it's a hassle to manage downloads through my browser.
Oddly enough this problem seems to go away when I use a VPN. Are there certain regions that Danbooru blocks from using download managers? So far I haven't encountered this problem with any other site, so I suspect there may be something on Danbooru's side that's interfering.