I only have internet through a 4G hub and the 4G signal sucks next to my computer, so I want to move the hub to another room. I have an iMac with an airport express creating my network. I want to create my network at my computer because it works better for streaming directly to my Apple TV's. Can I plug my 4G hub into another airport express in another room and add them to my network extending the network? I though the internet has to be connected to the initial router that is creating the network.