Connection Issues + Audio Issues

So we own 2 doorbells, both bought at the same time + same place. One is for our house and the other is the in-laws who live ‘next door but one.’ There doorbell has never connected- we assumed it was our own fault and wifi related. But since their home was secure we never bothered to attempt to try fix this 😬 We changed the battery- still never worked and just left it at that. Until today… Due to our home being revamped, having multiple cars on drive. A busy house anyway, people in and out constantly. And plus home businesses meaning people do often come- and we’ve had people walk in without knocking more than once. Since about a year ago, the doorbell hasn’t had any audio. You can’t speak through the app and it just sounds like wind when you speak from the doorbell mic itself. So we thought why not swap over? Since there’s isn’t connected + ours has no sound?! However…. Today i’ve disconnected both (marked them so i didn’t get mixed up) and connected them. However, the connection issues are still occurring at our house on our wifi with the in-laws doorbell? I’ve googled everything, searched the website itself and there’s nothing. It doesn’t make sense that both houses on multiple different wifi’s have the same issue with the same device but other devices work connecting from the wifi routers. It seems like a device problem… what do we do?