ok, one last ditch effort. You can try it if you want to. I use an app on my phone called Fing. Its a network scanner and has some neat tools. You can download it, it has a premium service but just ignore that. It will scan your network and list all devices connected to it, their IP address, mac address, and available open ports. You can plug the PA in and scan your network. Maybe Fing will give you some information that your router app is not giving you.
Also, I'm not familiar with Pentair equipment. But in trying to help you I have googled a little bit. It looks like you can connect locally using the Screen logic app on your phone or the computer app. The one YouTube video I watch said the app would automatically find the PA if it was connected. I assume you have tried this and let the app try to find the PA and it failed?