I can't connect to the internet

Check your power cable and connections. Loose, disconnected, or damaged cables can cause issues. Ensure the power cable is securely connected to your router and plugged into a working outlet.
Calix U6txg, U4g, U4xg
- Confirm the LED indicators for Power, PON, Internet, and WLAN are solid green or cyan. If they’re off, check the power supply.
- If the PON indicator is off or flashing red, there’s a fiber issue. Contact us via chat for help.
- If the WLAN indicator is off, press the Wi-Fi button on the router. If it stays off, contact us via chat for assistance.
Calix U6t, U4m (two-box: separate Calix RG and ONT)
- Ensure the router and ONT are connected via Ethernet and both are powered on.
- Connect one end of the Ethernet cable to the router’s black WAN port and the other to the ONT’s Ethernet port.
- Check ONT indicators. Power, PON, Service (or Internet), and Ethernet (LAN) should be solid green. If not, unplug the ONT for 10 seconds, then plug it back in and wait 2–5 minutes.
- Once restarted, check if the router's LED is solid cyan. If it’s off or flashing red, reboot the router by unplugging it for 30 seconds, then plugging it back in. If the red LED persists, contact us via chat.
Check router LED status. A solid cyan light indicates a good connection. Flashing red means the router can’t obtain internet. Check the WAN cable and reboot the router.
Temporarily disable any VPN or firewall settings on your device – they may block connectivity.
If you're still offline, reboot your device by unplugging and reconnecting the power cable.
Check your connection status in the T-Mobile Fiber app. Don’t have it? [Download for Android] or [Download for iOS].
In the app, go to My Network > Network Map to verify if your router is online.
Under the Things tab, confirm if your devices are connected.
Run a Bandwidth Test in the app to check connection speed and stability.

My internet connection is slow

Check power and connections. Loose or damaged cables can affect speed. Make sure your router is securely powered.
Run a speed test in the T-Mobile Fiber app:
- Go to My Network > Bandwidth Test > Run Test.
If speeds are still slow, reboot your router by unplugging it for 30 seconds, then plugging it back in. Re-run the test afterward.

One or more of my devices won't connect to the internet

Turn Wi-Fi off and on again on the device. If that doesn’t help, restart it.
In the T-Mobile Fiber app, check if the device appears under Things and is active.
If not, reboot the router by unplugging it for 30 seconds, then plugging it back in.
After rebooting, try reconnecting the device and verify its status in the app.

Does T‑Mobile Fiber have data caps?

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