To set up Deco X50 mesh routers, follow these steps: 1. Download the Deco app from the App Store or Google Play. 2. Open the app and follow the on-screen instructions to create a TP-Link ID and log in. 3. Connect your Deco unit to your modem and power it on. 4. Follow the app instructions to complete the setup process, including adding additional Deco units if needed. 5. Once setup is complete, you can manage your network settings through the Deco app.