Cannot Download Realms Backup

Hello. I will have to cancel my Realm subscription, and I wanted to download my world to Singleplayer before I lose it in 5 days, but every time I try to download, it fails before it completes. The percentage it fails at varies, and I've tried restarting my router, and making sure nothing is running in the background, but to no prevail. I have 5 days left to get this working, or my world of over two years is gone. Does anyone know what to do?