App not giving notifications on data

[Paul 880]

I have a S23 FE first samsung in many years,  I am a retained fireman so have a app (IaR) which pages us for fire calls, I'm having problems with the app not working on data as such I am missing important call out for fire calls ect . I have battery saver on the app off as well as notifications on set for data and wifi , what am I missing ? If I'm with in wifi I get no problem and receive call outs, any help is appreciated