Also brainfarting here but just in case: If you have a mechanical chime, make sure you provide enough juice. I have had no problems with this doorbell but I previously converted an old electronic chime back to a mechanical chime and combined with a video doorbell taking up to 10-12w peak, you may have a problem with voltage transients. Your transformer should be at least 20VA (e.g. 20W). Voltage does not matter so much unless you have very long circuit wiring in the house, higher voltage is better as you will pass lower currents and have lower line power loss. Most devices specification support 8-24V but 18-24V would be better. I am reading Amazon reviews and people having problems either are related to poor wifi setup (running on 2.4GHz), phone coverage and android app issues (android apps in general are much flakier due to breadth of devices they need to support and much less stringent requirements compared to iOS) to get their notifications, or power supplies. It is also why there are so many less than stellar reviews of video doorbells... many times it's not the doorbell, it's something else.