Updated to Windows 8.1, ethernet connection to router "unidentified network"

its quite safe

any other device you can plug into the power line to test at all ?

What firewall / security suite or anti-virus do you currently have on the PC - or you have ever had on the PC in the past - any trial ware - like Norton, kaspersky or Mcafee or any free security suites like zonealarm, AVG , Webroot etc

try a tcp/ip reset
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TCP/IP stack repair options for use with Vista/Windows 7/Windows 8

For Windows Vista/Windows 7

Start> Programs> Accessories> and right click on Command Prompt, select "Run as Administrator" to open a command prompt box (A new dialogue box - black with white font, will appear on the screen ):

For Windows 8

To open a Cmd Prompt or an Administrator Cmd prompt from the Desktop. Use Win + X and choose Command Prompt or Command Prompt (Admin) from the list.

In the command prompt window that opens, type the following commands:

Note: Type only the text in bold and red for the following commands.

• Reset WINSOCK entries to installation defaults: netsh winsock reset catalog and press enter

• Reset IPv4 TCP/IP stack to installation defaults. netsh int ipv4 reset reset.log and press enter

• Reset IPv6 TCP/IP stack to installation defaults. netsh int ipv6 reset reset.log and press enter

ReStart (reboot) the machine.

If you receive the message

The requested operation requires elevation.
Then please open the command prompt as administrator - as requested above
Start> Programs> Accessories> and right click on Command Prompt, select "Run as Administrator" to open a command prompt box (A new dialogue box - black with white font, will appear on screen ):

Please note and post back - if you receive the following message :-
Access is Denied

please post back the results in a reply here - its important we know that these commands have worked correctly and not produced any errors
right click in the command prompt box
select all
enter
control key + C key - to copy
then reply here and
control key + V to paste

Details also here
http://support.microsoft.com/kb/299357
also the link has a Microsoft Fix it , which will do the above for you

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