API 연결이 안됩니다.

.env 설정을 아래 3가지로 해 보고, 이것도 안되서 실제 아이피로 해 봤는데도 애뮬레이터 아래 undefined라는 오류 메시지만 뜨네요

; API_URL = http://192.168.0.255:3105
API_URL = http://10.0.2.2:3105
; API_URL = http://localhost:3105

SignUp.tsx 는 아래와 같이 되어 있습니다.

try {
      setLoading(true);
      const response = await axios.post(`${Config.API_URL}/user`, {
        email,
        name,
        password,
      });
      console.log(response);
      Alert.alert('알림', '회원가입이 완료되었습니다.');
    } catch (error) {
      const errorResponse = (error as AxiosError).response;
      console.error(errorResponse);
      if (errorResponse) {
        Alert.alert('알림', errorResponse.data.message);
      }
    } finally {
      setLoading(false);
    }

해당 패키지도 모두 설치하고, 서버도 재시작하고 했는데도 안되네요.

포트스맨으로 http://localhost:3105로 post 요청을 해 보면 아래와 같은 오류가 뜹니다.

TypeError: Cannot read properties of undefined (reading 'toLowerCase')
    at /Users/xxx/React-Project/React-Native/back/app.js:104:27
    at Layer.handle [as handle_request] (/Users/xxx/React-Project/React-Native/back/node_modules/express/lib/router/layer.js:95:5)
    at next (/Users/xxx/React-Project/React-Native/back/node_modules/express/lib/router/route.js:137:13)
    at Route.dispatch (/Users/xxx/React-Project/React-Native/back/node_modules/express/lib/router/route.js:112:3)
    at Layer.handle [as handle_request] (/Users/xxx/React-Project/React-Native/back/node_modules/express/lib/router/layer.js:95:5)
    at /Users/xxx/React-Project/React-Native/back/node_modules/express/lib/router/index.js:281:22
    at Function.process_params (/Users/xxx/React-Project/React-Native/back/node_modules/express/lib/router/index.js:341:12)
    at next (/Users/xxx/React-Project/React-Native/back/node_modules/express/lib/router/index.js:275:10)
    at urlencodedParser (/Users/xxx/React-Project/React-Native/back/node_modules/body-parser/lib/types/urlencoded.js:100:7)
    at Layer.handle [as handle_request] (/Users/xxx/React-Project/React-Native/back/node_modules/express/lib/router/layer.js:95:5)
POST /user 500 7.179 ms - 2

 LOG  Ghh@ch.bd Fhhh fggg@#_322
 LOG  Config::: undefined
 ERROR  undefined

 LOG  Dfsdf@sdfsd.ffd Dsd tewt!@#123qwe
 LOG  Config::: http//localhost:3105
 ERROR  undefined

; API_URL = http://192.168.0.255:3105
; API_URL = http://10.0.2.2:3105
API_URL = http://localhost:3105

 LOG  Fewer@wer.wer Werwer werwerwer!@#123
 LOG  Config::: undefined
 ERROR  undefined