# Retrofit unable to resolve host

**URL:** https://discuss.kotlinlang.org/t/retrofit-unable-to-resolve-host/17130
**Category:** Android
**Created:** [April 14, 2020, 3:28pm UTC](https://discuss.kotlinlang.org/t/retrofit-unable-to-resolve-host/17130 "2020-04-14T15:28:24Z")
**Posts on this page:** 2
**Page:** 1

<div class="post-metadata">

### Author: ![HydraRock](https://avatars.discourse-cdn.com/v4/letter/h/94ad74/32.png) [@HydraRock](https://discuss.kotlinlang.org/u/HydraRock)
#### Post date: [April 14, 2020, 3:28pm UTC](https://discuss.kotlinlang.org/t/retrofit-unable-to-resolve-host/17130/1 "2020-04-14T15:28:24Z")

</div>

Hello,  
I am trying to call an API through retrofits.  
The url that I call, is located on a server, in which at this moment I access go VPN.  
The token I am sending right now is good.  
I have tested everything via postman and it works correctly.  
Instead when I call through Android studio I get the exception “retrofit unable to resolve host”.  
I have made various changes to the code, according to some examples found on the net, but I can not solve the problem.  
If I use the same code to access the public bees of “[jsonplaceholder.typicode.com](http://jsonplaceholder.typicode.com)” everything works correctly

```
    // var urlConnection: String ="http://iswvgenint03/api/"
     var urlConnection: String ="http://172.20.26.375/api/"
     override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
    var miocontext = this.baseContext

    // textViewResult= findViewById(R.id.text_view_result);

    val clientBuilder = OkHttpClient.Builder()
    var authTokenBearer ="Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiJ9.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.nYf6SBlOE0AFEenWD8yLBPewyTQ9kMinCnL5eVEblZ_4CXKSbct-plvoJ7iIpugCdAiTJjiDWD4vNLIQ_ylzp93s8wctHbN2HLbZg_t-20CJwt8HQK0AmOup_jT3ayomGVOym0_ptmJNnzT6ozvmOkuYZtf5OQ0BCNuLJF4oVw1L6-KB0AXdigV-8UPbRehkuVRdTj8V1zrZqlyDGAIqDKm72UkmCtD3PTQASi428ZExSAZnfkiVF1TvloGpaeSPbhMwClX6KO5xr5ZJ9o75sCCrc8Onhtb80w43O3YH02U3PaYFd6TKL7p6ipphszg7kALeAQDSFxuUE9SJ_G3P5w"

        @Throws(IOException::class)
        override fun intercept(chain: Interceptor.Chain): okhttp3.Response? {

            val original = chain.request()
            val request = original.newBuilder()
                .header("Authorization", authTokenBearer)
                .method(original.method(), original.body())
                .build()

            return chain.proceed(request)

        }
    }
    //Add the interceptor to the client builder.
    clientBuilder.addInterceptor(headerAuthorizationInterceptor)
    val client: OkHttpClient = clientBuilder.build()

    var retrofit = Retrofit.Builder()
        .baseUrl(urlConnection)
        .client(client)
        .addConverterFactory(GsonConverterFactory.create())
        .build()

    val jsonPlaceHolderApi = retrofit.create(JsonPlaceHolderApi::class.java)

    val call = jsonPlaceHolderApi.getClients()

    call.enqueue(object : Callback<List<Client>> {
        override fun onResponse(call: Call<List<Client>>, response: Response<List<Client>>) {
            if (!response.isSuccessful) {
                // textViewResult.setText("Code: " + response.code())
                return
            }

            val posts = response.body()!!
        }

        override fun onFailure(call: Call<List<Client>>, t: Throwable) {
            Log.d("errot",t.message)
        }
    })

}

```

in an interface file I have  
@GET (“Clients”)  
fun getClients (): Call \<List \>

**I arrive always in onFailure**

The error messages I get are  
java.net.UnknownHostException: Unable to resolve host “iswvgenint03”: No address associated with hostname  
if I use the url

java.net.UnknownServiceException: CLEARTEXT communication to 172.20.26.375 not permitted by network security policy  
if I use the ip address

I think android studio can’t get to the url via vpn.

Do you have any solution for me?  
Thanks

---

<div class="post-metadata">

### Author: ![HydraRock](https://avatars.discourse-cdn.com/v4/letter/h/94ad74/32.png) [@HydraRock](https://discuss.kotlinlang.org/u/HydraRock)
#### Post date: [April 17, 2020, 2:18pm UTC](https://discuss.kotlinlang.org/t/retrofit-unable-to-resolve-host/17130/2 "2020-04-17T14:18:59Z")

</div>

I solved it by adding this code to the manifest.xml file

```
  <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
  <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
  <uses-permission android:name="android.permission.INTERNET" />
  <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

   android:usesCleartextTraffic="true"

```

Then chased I found that Retrofit was unable to resolve the url with the VPN so everything worked with the ip address  
and finally I modified the call in the interface

from so

```
    @GET("Clients")
    fun getClients(): Call<ClientList>

```

to

```
    @GET("Clients/")
    fun getClients(): Call<ClientList>

```