Question: Does it work if plugged into an outlet in a shop in the yard?
Answer: YES! But the quality of the signal and the connection speed is dependent on the distance from your main router and obstacles and radio interference on the way.
Question: does it have an Ethernet port , Does it come with an ethernet cable? Can you use the ethernet port to plug something in
Answer: Yes and Yes. It does have an ethernet port and extender came with the ethernet cable. You can connect the extender to your device with an Ethernet cable, also it could be work without an internet router, in “router mode”. Mainly I use the ethernet port when playing Playstation and box, Roku / Fire stick tv streaming, this way eliminates buffering or lagging, it has worked extremely well!
Question: will this increase my wifi speed or expend my coverage?
Answer: It will expend coverage. So let's say you have a modem with 100mbs speed and downstairs you can only get 10mbs by using this you will get more than 10mbs downstairs.