1. Is the router connected directly to the dish? If so (and assuming your router is inside the house, there is nothing to stop you having as many Ethernet connections as your TP-Link has ports. Think of it as a hardwired way of connecting devices such as your pc, laptop, phone, etc. It is nobody’s business how you distribute the signal inside your house.
2. If however your entertainment box connects to the dish (like James says), they may have a case. Some boxes allow one to “daisy chain” two boxes to the same satellite link, but most need a direct link to the dish, and even when daisy-chaining works, there are some technical limits on line impedance and such like.
3. In case 1. You could test it by getting another Ethernet cable and connecting the entertainment box to your router via an unused port. There is a technical limit to the length of run of Ethernet cable, but it is typically longer than what is needed in a dwelling. There may be a signaling encryption technology in operation which would only allow you to connect one android box at a time, but that does not seem to be your problem anyway.