Server not found for particular website

hoof

I have a Windows 7 PC running Norton Internet Security and have recently started having a problem accessing www.telegraph.co.uk. I keep getting server not found. My normal, preferred homepage is google news and if I click on a telegraph article I also get server not found. Clicking on a link to the same telegraph article via MSN News works.
Our other pc's in the house do not have this problem, and neither do our ipads/iphone - just my pc.
I have tried various “fixes”, unsuccessfuly, as follows: 1) We upgraded to fibre yesterday from ADSL and had to move to new router. I had hoped that this would fix my problem, but no. Re-set new router as well, but didn’t fix. 2) In Firefox Options, Advanced, Network I have tried:
a. Clearing cached web content b. Clearing Offline web content and data c. Also tried Clear history, recent history, everything d. Connection settings were same as other pc: Use system proxy settings. I did try auto detect option but this did not fix. Have, for now, switched back to Use system proxy settings. e. Tried Firefox reset, to no avail f. Tried running Firefox in Safe mode with add-ons disabled, bHave also done re-install of firefox and run malwarebytes, full scans.
A solution to this hugely frustrating problem would be appreciated.

hoof

I seem to have sorted by going to Control Panel, Network & Sharing Centre, Local Area Connection, Properties, Internet Protocol Version 4, Properties and using Obtain an IP address automatically and Obtain DNS server adress automatically - this later one was, for some reason, set to Use this DNS address - which seemed to be my old router!!!! New router set up obviously didnt sort this out.......
Maybe this will prove to be of use to others in future.