First, seems you reserved the setting while flashing back. So you have 1.1 as IP address, not 8.1. You need to reset the firmware by pressing and hold the reset button for 10 seconds.

Seconds, you can only go to advanced settings because the browser cache. You can clear the cache of your browser or try another browser.

Or a trick, add ? at the end of the url

try 192.168.8.1/index.html?