Why Http call using Retrofit2 (and rxjava observer) always waits for 5 secs on Wifi (Android M Nexus 6) -

on nexus 6 android m (v23), calling http api using retrofit waits around 5 secs, before getting request hit on server. both phone , server on same wifi. browser on other workstation in same wifi gets results instantaneously (~40-60ms). opening same api android chrome on same mobile takes 5 secs. can issue delayed http call?

code: retrofit2/okhttp service factory

public class apigenerator {     public static string tag = apigenerator.class.getsimplename();     public static final string api_base_url = buildconfig.api_endpoint;     public static final gson gson = new gsonbuilder()         .setfieldnamingpolicy(fieldnamingpolicy.lower_case_with_underscores)         .create();     private static okhttpclient.builder httpclient = new okhttpclient.builder()         .connecttimeout(15, timeunit.seconds)         .writetimeout(15, timeunit.seconds)         .readtimeout(15, timeunit.seconds)         .addinterceptor(new interceptor() {             @override             public response intercept(chain chain) throws ioexception {                 request request = chain.request();                 response response = chain.proceed(request);                 return response;             }         }).addinterceptor(new logginginterceptor());      private static retrofit.builder builder =         new retrofit.builder()                 .baseurl(api_base_url)                 .addconverterfactory(gsonconverterfactory.create(gson))                 .addcalladapterfactory(rxjavacalladapterfactory.create());                 ..... 

retrofit2 service

public interface authservice {      @get("/api/v1/auth")     public void authenticate(@query("token") string token);      @post("/api/v1/signup")     call<object> signup(); } 

service call -

observable<response<signupv1response>> observable = service.signuprx(signupreq);     observable.subscribeon(schedulers.io())             .observeon(androidschedulers.mainthread())             .unsubscribeon(schedulers.io())             .subscribe(new subscriber<response<signupv1response>>() {                 @override                 public void oncompleted() {                     ...                 }                  @override                 public void onerror(throwable e) {                     ...                 }                  @override                 public void onnext(response<signupv1response> response) {                     if (response != null) {                         final int statuscode = response.code();                         if (response.issuccess()) {                             //                         } else {                             responsebody errorbody = response.errorbody();                             // show error                         }                     }                 }             }); 

at last found that, has nothing okhttp , retrofit. android networking issue, has ipv6 enabled, on andoid l (v21) , higher. if wifi network not correctly handle ipv6 (most routers including recent releases), these http client libraries takes few secs before getting response. refer issue - https://code.google.com/p/android/issues/detail?id=79576

for workaround, can tunnel local development server amazon ec2 ssh or use ngrok. works fine approach.