Have you tried hard-lining it?
If nothing else works you could try taking it back and having it replaced.
[spoiler]had to do that with my first one for a different reason: the hdmi port on the system broke.[/spoiler]
I believe phone and enthernet lines have different jacks (?) if i remember right. Phone ones have a slightly smaller box compared to the ethernet.
Regardless the wifi box is all the way on the opposite side of the house. I'd need over 20 ft.
Well the biggest problem i got is that my roommate went with the cheapest mb/s we could afford at the time thinking it'd be enough even though we're heavy gamers.
That plan expires soon and we're also moving to an apartment. So we're likely gonna have much less connection problems while also having better internet.