I recently threw together a new WSUS server (2012 R2) and struggled to get clients to download the updates. Updates were always failing with error code 0x80244019. Typically this would indicate that the file was not in the WSUSContent folder, but in this case that wasn't true. I could copy the URL from my windowsupdatelog file and paste it into IE (on the client) and save the file with no issues.
The only way I could ultimately get things working was to make a change in IIS. Specifically, I had to go into Request Filtering > HTTP Verbs, and allow theHEAD verb, which was disabled by default. Is this standard practice? We recently had a vulnerability assessment done and they dinged us on this, but we obviously can't disable it if it's going to break WSUS functionality.