react native TypeError network request failed

fetch("http://xx.xx.xx.xx/login.do?srt=2", {
    method : 'POST',
    body : JSON.stringify({
        SLoginCode : this.state.userName,
        SPasswd : this.state.userPwd,
        randCode : this.state.vertifyCode,
        m : 'login',
        language : 'cn',
        srt : '2'
    }),
    headers : {
        'Accept' : 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;',
        'Content-Type' : 'text/plain;charset=UTF-8',
        'User-Agent' : 'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/44.0.2403.89 Safari/537.36',
        'Host' : 'domain.xx.com',
    }
})
.then((response) => {
    console.log(response);
})
.catch((error) => {
    console.warn(error);
})
.done();