The AyrMesh Hub has an IP address of 10.x.y.1 (if your AyrMesh Network originates from an AyrMesh Router) or 101.x.y.1 (if your AyrMesh Network originates from another brand of router). The "x" and "y" numbers are the decimal equivalents of the last two hexadecimal numbers in the Hub's MAC address. The Hub has an internal DHCP server that provides dynamic addresses from 10.x.y.50 to 10.x.y.254 (101.x.y.50 to 101.x.y.254 if you don't have an AyrMesh Router).
So, to set up a device with a static address, simply set the address on the device to one between 10.x.y.2 and 10.x.y.49 (or 101.x.y.2 to 101.x.y.49). The device won't show up in the "devices" list on AyrMesh.com, so make sure you remember what address it is at. You have to determine what the "x" and "y" numbers are for each Hub; to do this, you can either translate the last two numbers in the Hub's MAC address to decimal with a calculator, or you can just join the Hub's network and look at the address it provides to your device.
For instance, a Hub with the MAC address of 00:27:22:01:02:13 will have the IP address of 10.2.19.1 (02 is the same in hexadecimal or decimal, and 13 hexadecimal is 19 in decimal), and you'd set the address to something between 10.2.19.2 and 10.2.19.49.
When you set the device's IP address to an address in that range, you'll set the netmask to 255.255.255.0, and you'll set the gateway to the Hub's address (10.x.y.1 - 10.2.19.1 in our example).
Note, of course, that you'll need to manually change the address on the device if it moves to another Hub.