Fix Ubisoft 'Connection Lost: A Ubisoft Service is Unavailable'

Updated: 11/29/2025

You try to launch Rainbow Six Siege or Assassin's Creed, but the launcher hangs on 'Initializing'. Then, the orange text appears: 'Connection Lost. A Ubisoft service is currently unavailable.'. This almost always happens when your local network settings conflict with Ubisoft's legacy server architecture, which struggles with modern IPv6 connections.

01. Method 1: Disable IPv6 (The #1 Cause)
02. Method 2: Check Date and Time
03. Method 3: Disable Proxy Settings

Method 1: Disable IPv6 (The #1 Cause)

Ubisoft's servers prioritize the older IPv4 protocol. If your computer tries to connect via IPv6, the handshake often fails.

Step 1: Network Connections

Press Win + R, type ncpa.cpl, and hit Enter.

Step 2: Properties

Right-click your active connection (Ethernet/WiFi) > Properties.

Step 3: Uncheck IPv6

Find Internet Protocol Version 6 (TCP/IPv6) in the list. Uncheck the box next to it. Click OK. Restart Ubisoft Connect.

Method 2: Check Date and Time

If your system clock is even 2 minutes off, the SSL certificate for the login server will be rejected.

Right-click your taskbar clock > Adjust date/time.
Click Sync Now.
Ensure your Time Zone is correct.

Method 3: Disable Proxy Settings

Ubisoft Connect cannot navigate through a Windows Proxy.

Press Win + I > Network & Internet > Proxy. Ensure 'Use a proxy server' is toggled OFF.