Yeah, I live in the UK. But here is a US plug if you live in the US.
Here's what the echo stuff is:
>Echo expands the coverage of a traditional in-home wireless router by adding wireless access points in areas where Wi-Fi reception is poor. All a customer needs is a nearby Bright House cable connection. The new service isn’t a traditional wireless repeater. Echo relies on a wired connection between the access point and your cable modem/router using Bright House’s existing coaxial cable inside your home. The result is faster, more reliable Wi-Fi.
I had this problem but solved it with these, which work over your electrical lines - and then hooked up a second wireless router to that to help with wifi on that side of the house.
I'm not quite sure I understand your setup.
You have a location where you connect your modem, but that is not where you computer should be?
There is something called homeplug, which runs ethernet over your power cable.
Although I wouldn't recommend it, as it's more expensive than just getting a wireless router and a wireless card. With a wireless router you can also connect several computers, were as the homeplug can only support one.