Polymer2.0 - polymer testing is failing with error

Question

When I try to test polymer elements and run polymer test command, I am getting below error

Installing and starting Selenium server for local browsers
----------
selenium-standalone installation starting
----------

---
selenium install:
from: https://selenium-release.storage.googleapis.com/3.0/selenium-server-standa
lone-3.0.1.jar
to: C:\Users\xxxx\AppData\Roaming\npm\node_modules\polymer-cli\node_modules\se
lenium-standalone\.selenium\selenium-server\3.0.1-server.jar
---
chrome install:
from: https://chromedriver.storage.googleapis.com/2.27/chromedriver_win32.zip
to: C:\Users\xxxx\AppData\Roaming\npm\node_modules\polymer-cli\node_modules\se
lenium-standalone\.selenium\chromedriver\2.27-x64-chromedriver
---
ie install:
from: https://selenium-release.storage.googleapis.com/2.53/IEDriverServer_x64_2.
53.1.zip
to: C:\Users\xxxx\AppData\Roaming\npm\node_modules\polymer-cli\node_modules\se
lenium-standalone\.selenium\iedriver\2.53.1-x64-IEDriverServer.exe
---
firefox install:
from: https://github.com/mozilla/geckodriver/releases/download/v0.11.1/geckodriv
er-v0.11.1-win64.zip
to: C:\Users\xxxx\AppData\Roaming\npm\node_modules\polymer-cli\node_modules\se
lenium-standalone\.selenium\geckodriver\0.11.1-x64-geckodriver



Error: Could not download https://selenium-release.storage.googleapis.com/3.0/se
lenium-server-standalone-3.0.1.jar: Error: connect ETIMEDOUT xxx.xxx.x.xx:443

error:   cli runtime exception: Error: Could not download https://selenium-relea
se.storage.googleapis.com/3.0/selenium-server-standalone-3.0.1.jar: Error: conne
ct ETIMEDOUT xxx.xxx.x.xx:443
error:   Error: Could not download https://selenium-release.storage.googleapis.c
om/3.0/selenium-server-standalone-3.0.1.jar: Error: connect ETIMEDOUT xxx.xxx.x.xx:443

    at Request.<anonymous> (C:\Users\xxxx\AppData\Roaming\npm\node_modules\pol
ymer-cli\node_modules\selenium-standalone\lib\install.js:286:12)
    at Request.g (events.js:292:16)
    at emitOne (events.js:96:13)
    at Request.emit (events.js:188:7)
    at Request.onRequestError (C:\Users\xxxx\AppData\Roaming\npm\node_modules\
polymer-cli\node_modules\selenium-standalone\node_modules\request\request.js:845
:8)
    at emitOne (events.js:96:13)
    at ClientRequest.emit (events.js:188:7)
    at TLSSocket.socketErrorListener (_http_client.js:309:9)
    at emitOne (events.js:96:13)
    at TLSSocket.emit (events.js:188:7)

For security reasons, masked IP address with 'x'

Note: I am using proxy and it is available in .bowerrc file and other bower downloads are fine without any issue