When it comes to accessing the configuration section of (almost) any modem or router, you need to use its assigned address, which is usually something like 192.168.0.1 or 10.0.0.1. While it's possible to change that number for flexibility, the recommendation is to not make changes and keep the factory address. Why? The key is that some Internet protocol addresses are considered public, while others must maintain a private profile.
It's something that has happened to us dozens of times: the router or modem loses connection, its internal configuration gets messed up, and we need to access it to fix the problem. Another common situation is buying a router whose factory settings are a real security nightmare, and the only way to set things right is manual adjustments. Fortunately, accessing the device's advanced interface isn't difficult, but if there's something that immediately catches your attention, it's the address. What about 192.168.0.1? What about 10.0.0.1? Where do these numbers come from, and why are they so important?
Everything that connects to this router via WiFi or physically will be 192.168.2.x.
Everything starts with the division between public and private addresses. The public IP address that the modem receives is assigned by the provider, and although in most cases it's dynamic, it can only be used by one device at a time. The public IP address is always visible (just type "my ip" in Google to find it), unless you decide to hide it with a special service (VPN, Tor, etc.). On the other hand, private IP addresses are reserved for local communications on a LAN, and they don't have the ability to "go out" to the Internet. "The Internet Engineering Task Force" and "Internet Assigned Numbers Authority" decided that private-use IP addresses should be "10.0.0.0 - 10.255.255.255", "172.16.0.0 - 172.31.255.255", and "192.168.0.0 - 192.168.255.255".
There are over 17 million IP addresses, a number large enough for any casual or extended private use. Now, what about IPv6? Private addresses also exist under the new protocol, in the configuration "fc00:: - fdff:ffff:ffff:ffff:ffff:ffff:ffff:ffff", roughly 2.65 x 10^36 addresses. An outrageous number, but we once thought the same of IPv4...
