Open the Sensi app, add the correct Sensi product and choose Connect to Wi-Fi, then follow the reconnection route for your exact model. Sensi smart, Touch, Touch 2 and Lite do not all use the same pairing steps.
A router replacement or changed Wi-Fi password usually calls for network reconnection rather than a new wiring installation. I would leave the working HVAC configuration alone and identify the thermostat model before changing anything.
Check whether the network or the thermostat is offline
Make sure the home internet connection is working and the thermostat screen is powered. If other devices cannot get online, resolve that wider problem first. A blank thermostat display needs a different investigation from an app-only offline message.
If you recently changed the network name or password, the thermostat may still have the old details. A phone automatically joining the new network does not update the credentials stored in other devices.
Have the new network name and password ready, and check the model’s supported Wi-Fi band. Stay near the thermostat during provisioning. Do not weaken router security or remove the device from the owner’s account as your first troubleshooting step.
Use the Sensi Touch 2 route for Touch 2
For Touch 2, the manufacturer’s model reconnection guide uses the Sensi app and a QR-code or PIN pairing process. In the app, choose the plus sign, select your product and choose Connect to Wi-Fi.
At the thermostat, open Menu, then Wi-Fi, and choose Connect or Reconnect to display the pairing code. Continue in the app and scan the code, or use the documented PIN alternative.
Enable the Bluetooth permissions needed for this setup. Select the supported home network, enter its password and finish the app prompts. The QR or PIN identifies the thermostat; the Wi-Fi password authorises it to join the router. They are not interchangeable.
Older Sensi smart and Touch models use different branches
The original Sensi smart route can depend on the display state and phone platform. The official guide distinguishes displays such as 00, 11, 22 and 33. Select what your thermostat actually shows instead of choosing a branch because a video looks familiar.
Some routes temporarily connect the phone to a Sensi Wi-Fi network. That local network may have no internet because its purpose is device setup. Stay connected for the provisioning stage when the legitimate app instructs you to do so, then return to your normal home network.
The earlier Sensi Touch also has its own touchscreen and phone setup options. Do not use Touch 2’s QR-screen instructions on a device that offers a different menu. Use the exact model section in the reconnection guide.
My recommendation is to follow one complete supported branch. Combining the opening steps from one model with a PIN instruction from another makes a recoverable network problem much harder to diagnose.
Keep Sensi Lite pairing separate from a reset
Sensi Lite has its own product selection and pairing sequence, including the code supplied with the device and Bluetooth-assisted provisioning. Use its branch rather than guessing at a long button hold.
If you need to read a code from the device, follow its removal instructions and avoid disturbing the wiring or mounted base. The pairing code and the account password should not be published in a screenshot.
A factory reset can remove settings that were unrelated to the router change. Reconnection is the smaller, more relevant action when the thermostat already controls the equipment correctly.
If reconnection stalls, record where it fails
Failure to discover the thermostat suggests a pairing or permissions issue. Failure to see the home network suggests band, signal or network-visibility questions. A password rejection suggests credentials or unsupported security settings.
A device that joins Wi-Fi but remains absent from the app may have an account, registration or service issue. Check that you are signed into the intended owner account and viewing the correct home.
Restart the app or phone when appropriate and check the required permissions. If a router restart is needed, consider that other household devices will briefly lose connectivity. Avoid changing several router options at once because that removes the ability to identify what helped.
For support, collect the model, displayed message, phone operating system and failed stage. Provide the network band and router model when relevant, but do not send the Wi-Fi password in a public support thread.
Finish by checking the schedule and a small remote change
Confirm the app shows a current temperature, then make a small reasonable setpoint adjustment and check that the wall device reflects it. Restore the intended comfort setting afterward.
Check whether the device is following its schedule or sitting in a hold. Reconnecting Wi-Fi should not leave the household with an unintended permanent override.
If the thermostat repeatedly drops offline after a successful setup, investigate signal, power and the specific error rather than repeating the entire process indefinitely. A stable supported connection is the goal; a temporary success message is only the beginning of verification.