REG99 "Unable to connect"

Thanks everyone for all of your invaluable advice!  I went out of town with the phone and, when I logged onto my other wi-fi network at a different location (using my own router and NOT the one I rent from Comcast), the phone worked beautifully on the wi-fi calling.  I'm now convinced that it has something to do with the router at my other location in Maryland and I will check it out when I get back there in a week or so.