Boris Sprinkler
Dont be scared
the firewall (router) has its own webserver. That will be listening on 80 + 443. If you are scanning that from your computer it will return those ports as open. Since they are.
Depending on the model, it may also have service ports open (21,22,23).
But you want to be concerned with what is open to the internet from your host machine (the computer you are typing from).
A simple way of checking this is go here and enter your public IP. Online Nmap scanner - nmap.online
To find your public IP. go to here: What Is My IP? Shows Your Public IP Address - IPv4 - IPv6 and find your IPv4 address.
Depending on the model, it may also have service ports open (21,22,23).
But you want to be concerned with what is open to the internet from your host machine (the computer you are typing from).
A simple way of checking this is go here and enter your public IP. Online Nmap scanner - nmap.online
To find your public IP. go to here: What Is My IP? Shows Your Public IP Address - IPv4 - IPv6 and find your IPv4 address.