Can ordinary broadband cats be replaced by optical fiber broadband? If not, what should I do?

No, when you say ordinary broadband cat, you mean telephone line. That kind of cat is also called modem, which converts point signals into digital signals, while optical fiber needs optical cat, which is a modem that converts optical signals into digital signals. If you used to surf the Internet by telephone line, but you need to change it to optical fiber, you need to change it to optical cat. Generally, after finishing the fiber-optic broadband, the installer will bring a light cat to install it. You don't know what the situation is. We usually give light cats to users for free here. If you are asking how to replace the telephone line with optical fiber, it depends on which service provider in your community covers the fttp in your community. If there is no service provider covering optical fiber in your community, optical fiber broadband is basically not needed. You can ask about your property.