Ring Doorbell 2 Unacceptable Delay

I have no idea what a tag is so have just added to whatever is shown. But here goes Hi again. I think I have posted on here before but just cannot find it. We purchased a Ring Doorbell 2 approximately 18 months ago but the sound is difficult to hear and broken up and, the most annoying problem of all, is the notification delay. I have changed our broadband provider and moved the router as close as possible to the unit but it's made no difference whatsoever. Yesterday I took notice of the postman coming up our communal driveway. Firstly, to our house and then to our neighbours. He had actually gone back down the driveway and back onto the footpath before the unit activated. I counted approximately some 14 - 15 seconds. This cannot be correct - Cant it? This is currently operating on battery power, which is charged regularly, but was thinking of adding a permanent power supply, but not entirely sure if tis will make any real difference though? I can see there are many, many similar issues being reported but there doesn't seem to be an answer. Any advice please before I take it out and bin it?