When you connect to the Internet you use your Internet Service Provider’s (ISP) gateway/router modem. ISP’s want to control and manage the gateway. They do that using port 7547. So, what keeps a hacker from coming through that port?
An ISP that is up on security will restrict use of that port. They will set the gateway to only respond to traffic on that port if it comes from the ISP’s computers.
You can check to see if that is your case. See WordFence’s article and use their scanner: Check if Your Home Router is Vulnerable. If you are vulnerable, they explain what to do.