@VanSquished 

Have you tried http://tplinkmodem.net? I think the PC browser might remember the old entry. You could also clear the browsing history and try again.

 

Thanks for the information Heidi. I tried using the other address with the same result. I was using a ether net connection. I cleared out the browser history to no avail - and eventually used a different laptop over the wi-fi to set up the configurations. However, although my main PC worked ok over a wi-fi connection afterwards, the ethernet connection refused to play. I tried lots of different /ipconfig flushing stuff commands to try and coax it back into life. Also without success. Eventually I went for the nuclear option and deleted the ethernet controller (but not the driver) inside Network adapters in Device Manager then restarted the system. Bingo - it just worked!