Symptoms:
The install app is stating that the Wi-Fi password is incorrect, even though the password has been confirmed to be correct.
Why It Happens
This is caused by a known incompatibility between the HC and certain Comcast/Xfinity (Vantiva) routers. The connection failure presents as a password rejection even though the password is correct.
Troubleshooting Steps
Install a Wi-Fi extender. Recommended model: TP-Link AC750 Wi-Fi Range Extender (RE205). Connect the system to the extender's network instead of the main router.
Alternatively, if the customer is willing, ask them to split their router's network into separate 2.4GHz and 5GHz SSIDs and connect the system to the 2.4GHz-only network.
For the full list of affected router models and MAC prefixes, see article 1.3 Unable to Connect to the Home Controller.