With the Internet down, so was my Internet phone. And I hadn't changed my forwarding number. I still had it setup to forward my incoming calls to my apartment in Maine if there was a problem with the Internet connection. I have changed that. The calls will be forwarded to my sister's cell phone if the Internet connection goes down again.
The problem happened to be that the router was trying to connect with the wrong password. I found that out from the automated troubleshooter at AT&T tech support. I found out that Dave changed his email password. That email account also happens to be the main account, so the login password changed as well. But the router was still trying to connect using the old password.
I saw in my call log that I missed Dan's call last night. His call was forwarded to my empty Maine apartment.