Fix Hytale Server Authentication and UDP/QUIC Port Issues
Authenticate a Hytale server, open UDP 5520 and diagnose QUIC, NAT, firewall and exact-version compatibility.
Hytale uses QUIC over UDP, not TCP, and listens on 0.0.0.0:5520 by default. The server must also authenticate with Hytale services before accepting players. Treat these as separate layers: successful authentication does not prove the network path is open.
Authenticate the server
On first launch, run in the server console:
/auth login device
Open https://accounts.hytale.com/device, enter the displayed code and authorise before expiry (the manual example gives 900 seconds). On success, the server stores credentials in auth.enc and auth.key.
Treat both as secrets: never publish them or commit them, and restrict file permissions to the service account. Move them only through a secure channel during migration. Providers authenticating many instances should follow the dedicated provider guide rather than manually reusing one setup.
Configure bind and QUIC firewall rules
Default is 5520. To change it:
java -jar HytaleServer.jar --assets Assets.zip --bind 0.0.0.0:3500
Allow the same UDP port in the host firewall and, behind a router, forward it to the server's stable LAN address. Player traffic does not need a TCP rule.
| Check | Expected | Common error |
|---|---|---|
| Bind | 0.0.0.0:5520 or chosen port | Listening only on 127.0.0.1 |
| Host firewall | Inbound UDP allowed | Rule created for TCP |
| Router | External UDP to same LAN port | DHCP target changed |
| Client | Public address and actual port | Using private IP from Internet |
| Version | Matching protocol hash | Updated client, old server |
Diagnose in the right order
Read authentication output
Authentication successful and no renewal error. If the code expires, create a new one rather than reusing it.Confirm local listening
Test externally
Check NAT and ISP
Align client and server
Validate the fix
Test an external connection, world movement, reconnect and server restart. Confirm credentials persist, the port remains stable and firewall rules are permanent. Back up universe/, but protect authentication secrets separately.
The Hytale update guide resolves protocol mismatch; the backup guide protects the world before changes.
Avoid QUIC and NAT issues
Compare Hytale servers with ready UDP networking, public IPv4 and managed updates.
Frequently asked questions
Which port does a Hytale server use?
--bind, allow and forward the exact new UDP port.Why does a port checker say closed?
Why does auth succeed while players are rejected?
Primary source: official Hytale Server Manual.
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