Frame challenging is at the core of World Building. If I had more time on my hands, I would be adding more frame challenges to your question. As it is, though, I clenched at the part where you meant to use quantum entanglement for communication, and I stopped reading when you mentioned how the quantum device must be positioned. To give you an idea of how... Bad those things are, they are as offensive to sci-fi enthusiasts as the idea that the Earth is flat is offensive to the scientific community at large.
It is almost like saying that you can get a bike to hover by holding a magnet above it as you ride it.
So rather than claiming Nightmayre has posted a non-answer because it doesn't fit into the universe you are creating, consider that your universe may not be consistent and that answer is showing you why. It is doing its job so well that right now it is the must upvoted answer. It goes a long way into rethinking the world you are creating and then preparing a new, improved question on space warfare.
I would also suggest educating yourself about the science you invoke in your story. Quantum and FTL are not just buzzwords.
For the reason why your FTL communication device is a no-go, please see Quantum entanglement as practical method of superluminal communication
For the reason why the quantum entanglement device cannot be in a "center": you might just pull it off if both end points are on a planet, but as soon as they are not stationary relative to each other they will not measure space nor time the same way anymore. For light-year distances, this effect is just too much. Both ends will not be at the same pace, might not even agree on the order of some events they observe, much less where the "center" between them is. You can read more on that here.