you can not assign a public IP to your miner.
the public ip is assigned to your router.
what you need to do is this.
1- give your miner a static local ip (192.168.x.x)
2- go to your router setting
3- look for something that says "port forwarding" * we don't know your router model, so just google it or browse until you find it
4-forward a port to that static ip you gave to your miner, for example be it port 8080
5- access the miner from anywhere by tying your public ip address:port
for example say your public ip is 85.150.123.39 then on the browser you will type
note* if you only type
it will assume port 80 , which will be blocked by your router unless configured else wise, if you want to access the miner by only typing the public ip without any port then forward to
port 80 but it's not recommended.also make sure you change your miner default logins as you are now exposed to the outside word that is full of risk.