I have a nest Protect network consisting of four detectors. Three of them have been in use for several years with the fourth being added yesterday. The original 3 were working fine until I started to experience issues about two weeks ago - that was when I upgraded my router's firmware. SInce then, they have been having issues connecting to the app and to each other, I was able to completely remove them from the app and clear their settings. I was then able to add the original three and then the fourth. I even made sure they were connecting to a 2.4ghz network. I can press the test button and each detector will register with the app, but for a yet to be determined reason the interconnect is not completely working as the detectors are not talking with each other, In reading about the protects, this supposedly is independent from wifi. I even rolled back my router to see if that would fix the issue, which it did not. Is there anything else I can do to fix this, or is it time to get new alarms?
There are some things you can check. Does the wireless interconnect feature work if you bring them close together just to test?
I've linked a help centre article below that will help you troubleshoot this. Do let us know what happens when you try these steps? Try to be as detailed as possible so we know how best to advise.