RAXE500 Overriding my Static IP Addresses.

I have a RAXE500 Router. I have several devices on my network that have a static ip address. IE 192.168.1.18 and are wired.  Lets say for example I reboot my router for whatever reason. My router will sometimes assign any of my other devices that are set up as a dynamic ip and get their ip address from the router. So my router will just assign another device that ip. And not matter how many times I reboot the router will just not correct itself. So the device with the static ip will not work. I have no idea how to stop this from happening.   I turn off the device that it assigns the ip to then reboot and it will be ok. Then if a reboot happens it may do it to another device on the network that is set up as static.  Any ideas how to fix it?