Hi,
Brand new obi user here. This may be a less than ideal setup but it's what I'm using right now--primarily because of where my router is at the moment--I have the obi110 connected to our imac in which I've enabled internet sharing. So my signal chain is cable modem>time capsule>wireless to imac>obi110.
Only had the unit a week now I think, but it's been working very well. Still getting used to different things, like no names on CID, and don't really know about any of the other features besides dial tone, lol. Just thought I'd share another possibility that works.