com.google.firebase.FirebaseNetworkException: A network error (such as timeout, interrupted connection or unreachable host) has occurred.

I am a beginner and I followed all the steps mentioned in the [codelab](https://firebase.google.com/codelabs/firebase-android#5).
But I stuck here. I am okay to adjust if a codelab is not compatible to all the versions, and hence I will debug and fix issues. But I am tired of lots of issues which not have any clear information and support from firebase. Here is the stacktrace.
` A sign-in error occurred.
com.google.firebase.FirebaseNetworkException: A network error (such as timeout, interrupted connection or unreachable host) has occurred.
at com.google.android.gms.internal.firebase-auth-api.zzadg.zza(com.google.firebase:firebase-auth@@23.1.0:15)
at com.google.android.gms.internal.firebase-auth-api.zzaef.zza(com.google.firebase:firebase-auth@@23.1.0:21)
at com.google.android.gms.internal.firebase-auth-api.zzady.zza(com.google.firebase:firebase-auth@@23.1.0:32)
at com.google.android.gms.internal.firebase-auth-api.zzaea.zza(com.google.firebase:firebase-auth@@23.1.0:71)
at com.google.android.gms.internal.firebase-auth-api.zzade.zza(com.google.firebase:firebase-auth@@23.1.0:46)
at com.google.android.gms.internal.firebase-auth-api.zzzv.zza(com.google.firebase:firebase-auth@@23.1.0:3)
at com.google.android.gms.internal.firebase-auth-api.zzaeo.zza(com.google.firebase:firebase-auth@@23.1.0:67)
at com.google.android.gms.internal.firebase-auth-api.zzadv.zza(com.google.firebase:firebase-auth@@23.1.0:18)
at com.google.android.gms.internal.firebase-auth-api.zzzk.zze(com.google.firebase:firebase-auth@@23.1.0:128)
at com.google.android.gms.internal.firebase-auth-api.zzadh.zze(com.google.firebase:firebase-auth@@23.1.0:92)
at com.google.android.gms.internal.firebase-auth-api.zzabp.zza(com.google.firebase:firebase-auth@@23.1.0:15)
at com.google.android.gms.internal.firebase-auth-api.zzaeh.run(com.google.firebase:firebase-auth@@23.1.0:2)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
at com.google.firebase.concurrent.CustomThreadFactory.lambda$newThread$0$com-google-firebase-concurrent-CustomThreadFactory(CustomThreadFactory.java:47)
at com.google.firebase.concurrent.CustomThreadFactory$$ExternalSyntheticLambda0.run(D8$$SyntheticClass:0)
at java.lang.Thread.run(Thread.java:923)`