I created a resource pack that definitely works in single player, but it isn't working when I upload it as a server resource pack.
Steps:
1. bundle resource pack into a zip
2. upload zip to mediafire
3. double check that download url works
4. in server.properties edit resource-pack field with the download url
5 restart server
6. log in to server
7. when prompted, choose to download the resource pack.
8. resource pack finishes downloading but textures do not appear
9. look in server-resource-packs folder, expect to find [pack_name].zip but instead find legacy_[pack_name]zip without a '.'
Probably an issue with Mediafire. Use something that definitely supports direct file hotlinking such as www.uploadhosting.co, that works fine for me.