It could be related to an issue seen by most people if your mixer has not received an IP address from the DHCP server on your Router. One way to tell this is what is described in this article below:
If your mixer shows a "169.254..." address on it, this is a self assigned IP address for direct connecting of devices to each other (i.e. CS18AI connected directly to an RM mixer for AVB audio and communication over ethernet - with or without an AVB switch). You may want to check your router's connection, or power the router on long enough so that the devices speak to each other properly.
If you get a different IP address (that seems more like what your router gives) this would mean that your mixer is seen correctly and should connect.