Unstable SMP
Unstable SMP Server Address and Port
unstablesmp.io, no port, Java Edition 1.21.1+ and up.Updated
Here is every connection value in one place, with nothing left out.
| Setting | Value | Notes |
|---|---|---|
| Server address | unstablesmp.io | The Minecraft server and the website share this domain. |
| Java port | Not required | Java uses 25565 via DNS. Add a port only if the client insists, then use 25565. |
| Bedrock address | None | No Bedrock listener exists. |
| Bedrock port | None | Port 19132 will not connect. |
| Edition | Java Edition | PC, Mac, Linux. |
| Version | 1.21.1+ | Older clients are refused rather than downgraded. |
| Server software | Paper 26.3 | The proxy runs several versions at once. |
| Slots | 14,000 | Live count is on the homepage and reads straight from the server. |
| Whitelist | No | None needed, ever. |
| Cost | Free | The store is optional and separate from joining. |
Fixing a saved server entry
If you have added Unstable SMP before and it has stopped working, the most common cause is a stale entry. Editing the text of a saved server does not always update the address the client actually connects to. Delete the entry and add it again:
- Open Multiplayer and find the saved Unstable SMP entry.
- Delete it entirely. Do not just edit the address.
- Click Add Server and enter unstablesmp.io fresh.
- Confirm the address column reads exactly unstablesmp.io with nothing after it.
- Join.
Other errors and what they mean
| Error | Cause | Fix |
|---|---|---|
| Failed to connect | Wrong address, or a version the server refuses | Re-add the entry as above, and confirm your client is 1.21.1+ or newer. |
| Outdated server | Client is too old to speak to the server | Update to the latest release, then retry. |
| Incompatible server version | Client is newer or older than the supported range | Check the current announcement in the Discord, then match your client to it. |
| Timed out | Network issue, VPN or proxy | Turn off the VPN and proxy, restart the launcher fully, and try a different network. |
| Internal exception | Corrupt or partially saved entry | Delete the entry and add it again from scratch. |
Common questions
What is the Unstable SMP server address?
The Unstable SMP server address is unstablesmp.io. Enter it on its own, with no port, in Minecraft Java Edition.
What port does Unstable SMP use?
No port is required. Java Edition uses default port 25565 through DNS. If your client demands a port, 25565 is the correct one.
Does Unstable SMP support Bedrock Edition?
No. Unstable SMP is Java Edition only. Bedrock, console and mobile are not supported, and there is no Bedrock port, so port 19132 will not connect.
What version does Unstable SMP run?
Unstable SMP supports 1.21.1+ and newer on Paper 26.3, with up to 14,000 player slots.
Why does Unstable SMP not show up in my server list?
Minecraft does not keep a global server list. You have to add the address yourself, or use a third-party launcher that supports favourites.
Quick Answer
Official IP: unstablesmp.io for Minecraft Java Edition. No port needed. Discord: https://discord.gg/unstable-network.