How can I add Ethernet devices if all the LAN ports on my router are full?

You need an Ethernet switch.

A switch is simply a box that multiplies the number of LAN ports available in your network – think of it as the networking equivalent of an outlet strip for electricity. It works by simply transferring packets between the ports on the switch. It doesn’t route traffic between different networks like a router, it just moves traffic on a single network. As such, a switch can be connected to your network wherever you need extra Ethernet ports for your LAN.

Switches are handy if your router’s LAN ports are full, for instance, and you need to plug in your AyrMesh Gateway Hub – simply disconnect one device temporarily, plug in the switch, then plug that device into the switch. It will work exactly as if it was plugged directly into the router.  

A switch is also handy if you put an AyrMesh Remote Hub somewhere and want to connect more than one device to it: simply plug a switch into the AyrMesh Remote Hub and you have several more ports for wired devices on your AyrMesh network. Using a router, the Ayrstone AyrMesh network, and some switches can enable you to have a very capable, flexible network for your home and business, saving you time and money.