Doorbell2 Offline

I've had my doorbell 2 for about 3 years and it worked great for the first few. It's hardwired but now the battery needs to be charged every few months. My main problem is that it goes offline every few days and I have to reset it even when the battery is fully charged. My signal strength is good and the app tells me the wi-fi signal and power level are good. Not sure what to do to fix the offline problem. Should I replace the battery? Could the problem be a bad hardwire connection?Thanks for your help.