@Solla-topee hi thanks for your response . I believe that I have by accident sort of sorted problem out as I have now been able to access setup page . I was using Firefox to access TP-Link extender .net through the browser with wi fi dissconected with the Ethernet wire plunged into laptop and TP-Link extender. At first it didn't connect but brought a pop up from malwearbytes saying at blocked because of a Trojan ?.

Today I tried again this time with Firefox it displayed Error 404 (see pic) .

i now tried using Chrom instead of Firefox this seems to worked no warnings ,no Error codes no idea why this now allow access to Tp link extender. Not sure what will happen next time I try .

thanks for your Help Graham.