A one-page glossary of the words you'll run into when dealing with home fiber internet, WiFi, and routers — plain-language definitions, no circular jargon.
The box that directs traffic between the devices in your house (laptops, phones, TVs) and the internet. It also usually creates your WiFi network. This is the box you're most likely replacing with something better than the ISP-supplied one.
A device that translates the signal coming from your ISP (over cable, phone line, or fiber) into a format your home network can use. On a fiber connection, this job is done by an ONT instead — see below.
The fiber equivalent of a modem. It's the small box the fiber cable from the street plugs into; it converts the light signal into a regular Ethernet cable your router can use. On fiber internet, the ONT replaces the modem — you generally don't have both.
These are not the same thing, even though people use them interchangeably. WiFi is just the wireless connection between your devices and your router, inside your house. The internet is the connection from your router out to the rest of the world. You can have working WiFi with no internet (devices still talk to each other and to the router), or working internet with no WiFi (if you're plugged in with a cable).
A numeric address (like 192.168.1.42) that identifies a device on a network, the same way a street address identifies a house. Every device needs one to send or receive anything. Most home devices get one automatically — see DHCP below.
WAN (Wide Area Network) is the connection going out to your ISP and the internet — usually one specific port on your router, often labeled "WAN" or "Internet." LAN (Local Area Network) is everything inside your house — your other Ethernet ports, and WiFi. Traffic between your laptop and your printer stays on the LAN; traffic to a website goes out the WAN.
A login-based way some ISPs hand out your internet connection — your router has to authenticate with a username and password (supplied by the ISP) before it gets online, similar to logging into a WiFi network but for the WAN side. Not every ISP uses it; some just hand out a connection automatically. See the dedicated page for how to find and enter these credentials.
A way of splitting one physical connection into separate logical networks, tagged with an ID number. Some ISPs require your router's WAN connection to be tagged with a specific VLAN ID before the connection will work at all — without it, the ONT just won't hand out an address. See the dedicated page for more detail.
The automatic process that hands a device an IP address the moment it connects to a network, so nobody has to type one in by hand. Your router runs DHCP for your home devices; your ISP may or may not run DHCP for your router's WAN connection (if not, you may need PPPoE instead).
The device that sits between your local network and the wider internet — in a home, this is usually your router. "Gateway" and "router" are often used to mean the same box; ISPs tend to say "gateway" when referring to the combo unit they rent you.
A dynamic IP address can change over time and is assigned automatically (via DHCP) — this is the default for almost all home connections. A static IP address is fixed and doesn't change; it's usually an extra-cost option ISPs offer for people running a server or needing a stable address to connect back to.
How much data your connection can move at once — think of it as the width of the pipe, not how fast water moves through it. Higher bandwidth means more stuff (video streams, downloads, devices) can happen at the same time without things slowing down.
How long it takes a signal to make a round trip to a destination and back, measured in milliseconds (ms). Low latency matters for anything that needs to feel instant — video calls, online gaming. A connection can have huge bandwidth and still feel laggy if latency is high.
Easy to mix up. Mbps (lowercase b) is megabits per second — this is how internet speeds are almost always advertised. MBps (capital B) is megabytes per second — this is how file sizes and download progress bars are usually shown. There are 8 bits in a byte, so a "100 Mbps" connection tops out around 12.5 MBps in a download manager. The math isn't a bug, it's just a different unit.
Modern routers broadcast WiFi on more than one radio frequency band at once. 2.4GHz reaches farther and passes through walls better, but is slower and more congested (lots of devices use it). 5GHz is faster and less congested but has shorter range. 6GHz (on newer WiFi 6E/7 gear) is the fastest and least congested of all, with the shortest range. Most routers pick the best band for each device automatically.
The built-in software that runs a piece of hardware like a router or ONT — separate from any app you use to control it. "Update the firmware" means installing a newer version of that built-in software, usually to fix bugs or security issues.
Wipes a device's settings back to how it shipped from the factory — erases your WiFi name/password, any custom configuration, everything. Usually done by holding a small recessed button for 10+ seconds. Last resort when a device is misbehaving or you're handing it off to someone else.
A rule that tells your router "if traffic comes in on this specific port, send it to this specific device on my network." Normally your router blocks unsolicited traffic from reaching devices inside your house; port forwarding punches a deliberate, narrow hole for things like game servers or security cameras you want to reach remotely.
The part of your router (or a device) that decides which traffic is allowed in and out, blocking anything that looks unsolicited or suspicious by default. It's the main reason random traffic from the internet can't just walk into your home network uninvited.
The system that turns a website name you type (like google.com) into the numeric IP address computers actually use to find it — basically the internet's phone book. If DNS is misconfigured or down, websites can fail to load even though your internet connection itself is fine.
A setting that turns a combo modem/router unit into a "dumb" pass-through, disabling its own router functions (WiFi, DHCP, firewall) so it just hands the raw internet connection to a router you plug in after it. Useful when you want to keep an ISP-required box in the chain but let your own router do the actual work.
The technical name for a WiFi network's name — the thing you pick out of the list on your phone when connecting.
A seven-layer conceptual map of how networking works, from physical cables at the bottom to the apps you actually use at the top. You don't need to memorize it to fix your home network, but it's a handy mental model when troubleshooting terms reference different "layers" of the problem. See the dedicated page for a plain-language walkthrough.