I began this project by upgrading doorbell transformer to 24 VAC 40 VA, and then replacing one of two ancient, fading doorbells with DB1C, corresponding with installation of power kit on “rear” terminal at the chime. I had to set up an extender behind the exterior wall to provide sufficient Wi-Fi signal to the doorbell. The installation was smooth and quick, the doorbell and app came to life, and the doorbell sounded the mechanical chime when pressed.I’ve grown to appreciate the many settings in the app for customizing the operation of the doorbell alarm system. There’s plenty flora around here that generates loads of false action on windy days. The wide range of sensitivity options combined with customization of detection area are essential to keeping quantity of alarm notices under control and meaningful.I could not fault this new system so bought a second DB1C to replace the other doorbell, and wired the power kit to “front” terminal at the chime. There was no instruction for correctly wiring two power kits at the chime, so, not being an electrician, I did what seemed sensible to me, which was to have both power kits share the transformer terminal. I also added a Wi-Fi extender behind that doorbell’s location.When I had connected the second doorbell, it promptly came to life and also rang the chime, differentiating the chime sound for “front.” All was well.A couple days later, the mechanical chime stopped working, but, other than that, both doorbells continued to operate to perfection. Thinking I had made a wiring error, I tried a couple changes at the chime, but nothing worked, and neither did a reset of the doorbells.At that point, I contacted customer service with query as to how to properly wire two doorbells/power kits, thinking maybe the failure was due to a wrong guess on my part, as double-doorbells is not covered anywhere in their instructions. They replied with basic installation instructions in response — the information I already had and had done — and requested details like serial and model numbers, vendor, my phone number. In response, I was sent basic installation steps and links to two videos covering the basics — again.In subsequent emails they requested photos of chime wiring and asked me to use a voltmeter to measure current at various points of the doorbell circuit. Sigh. They suggested I wire in a second transformer, and put one doorbell on each. NO!They told me to delete each device in the app (as opposed to using reset button in each doorbell). This was in response to my suggestion that maybe I had inadvertently selected wrong chime setting, for which there is no app access to that setting except by resetting.Well, I did the deletion, happily discovering that reinstalling did not require a doorbell reset, so that I need not stand outside in the winter weather yet again. When I’d finished, the chime responded to each device button. YEA! And it’s continued to function properly for several days. And now I know how to solve the problem should the chime fail again. I guess deletion is synonymous with a hard reboot!Customer service was very attentive and responsive to me. Their information wasn’t always useful, but they were persistent; we worked together and eventually stumbled upon the correct solution! As for the doorbells and app, I am completely satisfied thus far and do strongly recommend the product. Its features are highly useful to me, and it’s surviving our late winter/early spring nasty weather.I also recommend using microSD for data storage, as there is no need to remove the card. It can be formatted via the app. All data can be retrieved via the app.