- Docker Hub - One private repo/image spot for free
- Three Scale - Very generous free tier 50GB of space, 500 Pulls a month etc..
- Canister - 20 private repos with almost no limits on free tier
- Code Fresh - Free tier for developers
- Setup Private Docker Registry - Digital Ocean hosted Tutorial
- How to set up a Private Docker registry - Quora on Setting up Docker registry
- 16 best Private Repos - slant summary/combined link
I had the same problem as you, so I looked for an alternative solution. Give it a try: https://docs.vultr.com/vultr-container-registry.