iPhone XR network exception

I have a vendor app that monitors our solar power system. It is installed on an iPhone SE and iPad and works flawlessly. But when I run the app on my iPhone XR most of the app pages always run fine yet 3 app pages always (and immediately) result in a pop up ‘network exception’ error msg. I contacted the app vendor, who has 1000s of users of this app, they have no known issues of this kind. Given my other 2 Apple devices work flawlessly I also have to wonder what setting in the XR could be causing this. I had done a network reset however absolutely no change in the ‘network exception’ message still showing up. All devices running lost current iOS.

any clues or thoughts as to why the XR having comm issues with a few specific pages on one specific app. Even if the suggestions are directed to the vendor, they seem to be willing to look at whatever is suggested.