Cannot do "flutter packages upgrade". I get socket error - gradle

Question

I am trying to start a new flutter project, I followed the getting started guide, installed android studio, flutter sdk, got a device working, added flutter package to VScode. you can see my flutter doctor output here:
D:\Workspace\flutter_app>flutter doctor -v
[√] Flutter (Channel beta, v0.8.2, on Microsoft Windows [Version 6.1.7601],
locale en-US)
• Flutter version 0.8.2 at C:\src\flutter
• Framework revision 5ab9e70727 (4 weeks ago), 2018-09-07 12:33:05 -0700
• Engine revision 58a1894a1c
• Dart version 2.1.0-dev.3.1.flutter-760a9690c2
[√] Android toolchain - develop for Android devices (Android SDK 28.0.3)
• Android SDK at C:\Users\baib37302\AppData\Local\Android\sdk
• Android NDK location not configured (optional; useful for native profiling
support)
• Platform android-28, build-tools 28.0.3
• Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
• Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1136-
b06)
• All Android licenses accepted.
[√] Android Studio (version 3.2)
• Android Studio at C:\Program Files\Android\Android Studio
• Flutter plugin version 29.0.2
• Dart plugin version 181.5616
• Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1136-
b06)
[√] VS Code (version 1.27.2)
• VS Code at C:\Users\baib37302\AppData\Local\Programs\Microsoft VS Code
• Flutter extension version 2.19.0
[√] Connected devices (1 available)
• Android SDK built for x86 • emulator-5554 • android-x86 • Android 8.1.0
(API 27) (emulator)
• No issues found!
I am working behind a corporate proxy, but I added this to environment variables: HTTP_PROXY : http://"user":"pass"#proxy:8080
As you can see, Everything looks great. The only issue is I cannot run the project, because running "Flutter run" starts executing "flutter packages get" which is not working due to a socket error when connecting to https://pub.dartlang.org. As you can see here:
D:\Workspace\flutter_app>flutter packages get
Running "flutter packages get" in flutter_app...
Got socket error trying to find package node_preamble at
https://pub.dartlang.org.
pub get failed (69) -- attempting retry 1 in 1 second...
This issue comes up when trying to run from android studio or vs code.
I even tried getting pubscpec.lock file from an example project to try to work around this issue, but that failed as running "flutter install" ends up with gradle error as you can see in:
Flutter crash report; please file at https://github.com/flutter/flutter/issues.
## command
flutter install
## exception
String: Exit code 1 from: D:\Workspace\flutter_app\android\gradlew.bat -v:
Downloading https://services.gradle.org/distributions/gradle-4.4-all.zip
Exception in thread "main" java.net.UnknownHostException: services.gradle.org
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:184)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:589)
at sun.security.ssl.SSLSocketImpl.connect(SSLSocketImpl.java:673)
at sun.security.ssl.BaseSSLSocketImpl.connect(BaseSSLSocketImpl.java:173)
at sun.net.NetworkClient.doConnect(NetworkClient.java:180)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:432)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:527)
at sun.net.www.protocol.https.HttpsClient.<init>(HttpsClient.java:264)
at sun.net.www.protocol.https.HttpsClient.New(HttpsClient.java:367)
at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient(AbstractDelegateHttpsURLConnection.java:191)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1138)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1032)
at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:177)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1546)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1474)
at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:254)
at org.gradle.wrapper.Download.downloadInternal(Download.java:58)
at org.gradle.wrapper.Download.download(Download.java:44)
at org.gradle.wrapper.Install$1.call(Install.java:61)
at org.gradle.wrapper.Install$1.call(Install.java:48)
at org.gradle.wrapper.ExclusiveFileAccessManager.access(ExclusiveFileAccessManager.java:65)
at org.gradle.wrapper.Install.createDist(Install.java:48)
at org.gradle.wrapper.WrapperExecutor.execute(WrapperExecutor.java:128)
at org.gradle.wrapper.GradleWrapperMain.main(GradleWrapperMain.java:61)