Just to be clear: We are talking about a StudioLive 24.4.2AI mixer? As far as I remember the USB port on this mixer is used mainly for upgrading firmware. It has no or limited WiFi function. Therefore you need to connect the mixer to the router via "Control" (on the option card). The mixer is then the "sender" of information for all remote devices.
Always let the router boot fully, if you use dynamic IP addresses. Then start the mixer, then the computer. It might be that you see two connections (two mixers) in UC Control on your computer. Usually the Firewire connection gets priority automatically after a few seconds (the WiFi connection disappears). If not, simply click on the Firewire symbol.