Yup - it has been going off line for some time. So I called shaw tech support. Yup - they could see it on their logs as well. So they sent their techs out. They found nothing wrong ... so they did a little "clean up" of the cables.
Here's the big news: the techs told me that it is a known problem that when you add an expander to the 3510 then there are regular communication problems between the 3510 and the expander which directly gives rise to the "Off Line Mode" error message. This is curious, as adding an expander is something which Shaw promotes.
QUESTION 1: Will the next software patch fix the problem ???
QUESTION 2: When will the software patch be released ???