Cannot access router page in Safari

I have a new ASUS router RT-AC68U when first set up I was able to access the page by typing in 192.168.1.;1 or router Asus etc. now I get the message Safari cannot connect to the server entering the actual IP address from the network settings produces the same result. I am therefor essentially locked out of my router and can make no changes, I also seem to have lost the 5Ghz band.

I saw no resolution to this previously is it a Safari issue I have no problem at all with my Linksys Velop router.

Ignore the topics I was unable to change them from the ridiculous list which did not include non Apple hardware or even Safari