When you hit the WLS Server via Proxy server, we may get the issue like below...

[09/Jun/2014:06:05:50] failure ( 3284): for host 127.0.0.1 trying to GET /.../soundlink_wireless_​speaker/index.jsp, wl-proxy reports: exception occurred for backend host '127.0.0.1/7001/0': 'PROTOCOL_ERROR [line 835 of URL.cpp]: Backend Server not responding'

[09/Jun/2014:06:05:50] failure ( 3284): for host 127.0.0.1 trying to GET /.../soundlink_wireless_​speaker/index.jsp, wl-proxy reports: exception occurred for backend host '127.0.0.1/7001/0': 'PROTOCOL_ERROR [line 835 of URL.cpp]: Backend Server not responding'

[09/Jun/2014:06:05:51] failure ( 3284): for host 127.0.0.1 trying to GET /.../soundlink_wireless_​speaker/index.jsp, wl-proxy reports: exception occurred for backend host '127.0.0.1/7001/7001': 'CONNECTION_REFUSED [os error=0, line 1715 of URL.cpp]: Error connecting to host 127.0.0.1:7001'

To solve the issue

1.  Check if there is any issue at the firewall by executing the below command

    telnet 127.0.0.1 7001

2.  Also access  using the hostname instead of IP Address

 If it errors out like below

  Microsoft Telnet> o 127.0.0.1 7001

connecting to 127.0.0.1 

Warning thrown at weblogic console:

<BEA-000449> <Closing socket as no data read from it on 127.0.0.1:54,356 during the configured idle timeout of 5 secs>

 Test the same again by disabling the firewall. Below are the steps...

1)Go to Start ----> Run

 2)Type services.msc

 3)In services.msc search for "Windows Firewall" and Right Click on "Windows Firewall"---->Select Stop.

4)Access the Weblogic URL

 If the issue is resolved after disabling firewall,

Request your  OS System Admin to open the port 7001 at the firewall end to access the application