We use it for our outside services. I set it on top of the box that contains the mixer. The iPad is less than 50' away with clear view. I need to check for clarity of signal and the band but nothing else should be using it because it is only sending signal for the mixer. How do I verify the frequency is clear? I was under the impression that a router/modem would keep us from dropping signal.
Your impression is wrong. You aren't even using a router or a modem. A modem is a device to convert analog signals to digital data. We used to use dial up modems now today DSL and Cable connections require them (as DSL and Cable are analog signals). A router forwards packets to networks outside your LAN. since your xr16 and your tablet are on the same network no routing is needed.
An access point is a device to connect wired to wireless networks. That is what you are using. Just because you TP consumer doodle wanker thingamgig includes a router in the same box it is important to understand what functionality is required.
I gave you all the steps to be successful. Remember even though your guests may not be using your network their phones still scan it and obtain information on it's capabilities. How else do you think the network would appear in a list? That's why not broadcasting the SSID was an included step.
Have you logged on to the box and looked at the settings? That's how you know what band you are on. There are apps available for phones that will scan for a free channel.