Thanks. Yes, it is most likely not a DNS issue, but since somebody claimed they fixed it (and then twice posted instructions on how to change the DNS), I wanted to definitively rule it out, which you have done.
My "educated guess" is that the OBi devices (regardless of model or firmware level) are trying to contact a Google server or servers, out of a pool of servers, that are dead and/or have been changed.
If I get any update from Obihai, I'll post it, but for now, this is a "Do not attempt to adjust your set" issue that can't be fixed by the user.