Offline use with XR18

Hello,

I'm using a Netgear R7000 offline. It's dedicated to connect my band's computer's, tablets and iPhones to a Behringer XR18 digital mixer. We use it to perform live. I need to change the password on the R7000, so that no one can access the router without my permission. I already know the current password but wish to change it. The router is never connected to the internet. I don't want former band members to have access to the mixer so this is why I need to update the password to access the R7000. Also, is it possible to change the settings of the R7000 to prevent cell phone users from finding the router at our gigs and attempting to connect? We need a stable connection only to those of us who use the R7000 at our gigs and studio sessions. Other devices might be trying to connect automatically and I've been warned can force our band connections to disconnect as a result, not good.  Thank you!