You could potentially use a command line sensor or binary sensor. I have not tested the below at all, just wrote it as a starting point for you.
Edit: I don’t know if curl is an accepted command inside hass.io or not, i have never tested it myself.
binary_sensor:
- platform: command_line
command: curl -i http://192.168.0.1
value_template: << PARSE OUT THE HTTP STATUS CODE, YOU ARE LOOKING FOR A HTTP 200 RESPONSE OR A HTTP AUTH REQUIRED CODE >>
payload_on: 200