I used to complain that when attempting to connect to my ISP that I would often get an Error Message: Error 678: The remote computer failed to respond in a timely manner. If I recall correctly, I would also get basically the same type of error message but with different error numbers as well. This problem would occur as often as 4-5 times a day. Increasing Maximum Port Speed and adding additional access phone numbers were of very little or no help.
About a month ago I read on the Internet that this type of error can sometimes be fixed by entering the login Username using upper case charactors i.e. XXXXXX@xxxx.xxx rather than email@example.com. And since changing my login Username to upper-case charactors and restarting the computer a month ago, I have not received the login errors.
I do not recall the web site where I read of this possible fix or why it worked, but since it has apparently fixed the problem I thought it might be helpful to pass along this information.