Expo unable to call remote API from react native app

Question

I have a react native app on a local machine which is to call an API from another local machine on the same networ with a fetch() method. But I keep getting this error

"Possible Unhandled Promise Rejected(id:0)" TypeError: Network request failed.

async function conversionRate() {
      try {
            let FC = global.code;
            let TC = global.des_code;
      const params = {
            method: "POST",
         headers: {
                 Accept: "application/json",
                 "Content-Type": "application/json",
                  },
         body: JSON.stringify({ FC: TC }),
         };
       console.log(url + "servicePost/getConversionRate");
       let response = fetch(url + "servicePost/getConversionRate", params)
                          .then((response) =\> response.json())
                           .then((data) =\> cnt(data));
                     // var responseJson =  response.text();
                   } catch (error) {
                             console.log(error.toString());
                               }
                    }