192.168.100.1 — Cable Modem Admin
If you're trying to access 192.168.100.1, you're looking at your cable modem, not your router. This is an important distinction that confuses a lot of people. Your router (at 192.168.1.1 or 192.168.0.1) is where you manage WiFi settings, passwords, and connected devices. Your modem at 192.168.100.1 is the device that connects to your ISP's cable line — it handles signal levels, DOCSIS channels, and your internet connection itself.
Most people never need to access their modem's admin page. The main reasons to visit 192.168.100.1 are: checking signal strength when troubleshooting slow internet, verifying your modem is online, or reading event logs that your ISP's tech support might ask for.
Modem vs. Router vs. Gateway
Understanding which device is which saves a lot of frustration:
Modem (at 192.168.100.1) — The box with the coaxial cable plugged into it. Converts cable signals to Ethernet. Has limited settings — you don't change WiFi here because modems don't have WiFi. Brands: Arris/Surfboard, Motorola, Netgear, Hitron.
Router (at 192.168.1.1 etc.) — Connected to the modem via Ethernet. Creates your WiFi network, assigns IP addresses to your devices, and handles all your network settings. This is where you change WiFi passwords and names.
Gateway (modem + router in one box) — ISP-provided devices like Xfinity's xFi Gateway or AT&T's BGW320 combine both functions in one device. If you have a gateway, you might not have a separate modem at 192.168.100.1 at all — your gateway's admin is at a different IP.
Logging Into Your Modem
Open http://192.168.100.1 in your browser. If it loads, you'll see a login page or directly see the status page (some modems don't require a login for read-only access).
| Modem Brand | Username | Password |
|---|---|---|
| Arris / Surfboard | admin | password |
| Motorola | admin | motorola |
| Hitron (Rogers/Shaw) | cusadmin | password |
| Netgear (modem mode) | admin | password |
| Technicolor | admin | admin |
What You Can See and Do
Signal Levels (Downstream/Upstream) — This is the most useful section. It shows signal power (dBmV), signal-to-noise ratio (SNR), and channel frequencies for each DOCSIS channel. Good downstream power is between -7 to +7 dBmV, and good SNR is above 33 dB. If your ISP asks you to "check your signal levels," this is where you look.
Connection Status — Shows whether the modem has established a connection with your ISP. You'll see the startup procedure: hardware initialization → downstream acquisition → ranging → DHCP → time of day → registration → complete. If it's stuck on any step, the modem can't get online.
Event Log — Records connection events, errors, and restarts. Useful for proving to your ISP that you're having intermittent disconnections ("here are 47 T3 timeout events from the past week").
DOCSIS Info — Shows your modem's DOCSIS version (3.0, 3.1, or 4.0), firmware version, and hardware specs.
192.168.100.1 Won't Load?
You have a gateway, not a separate modem. If your ISP gave you a single box that handles both modem and WiFi functions, it probably doesn't use 192.168.100.1. Try your gateway's IP instead: 10.0.0.1 (Xfinity), 192.168.1.254 (AT&T), or 192.168.0.1 (Cox).
Your computer isn't directly connected to the modem. Most modems are only accessible from a device that's directly connected to them via Ethernet. If you're connected to your router via WiFi, the modem might not be reachable. Try connecting an Ethernet cable directly from your computer to the modem.
The modem uses a different IP. While 192.168.100.1 is the most common modem IP, some use 192.168.0.1 or 10.0.0.1. Check the label on your modem for the correct address.
Your ISP disabled local access. Some ISPs lock down modem access on their rented equipment. If you can't reach the modem admin page at all, this might be by design — contact your ISP to confirm.
Reading Signal Levels
| Metric | Good Range | Acceptable | Problem |
|---|---|---|---|
| Downstream Power | -7 to +7 dBmV | -10 to +10 dBmV | Outside ±15 dBmV |
| Upstream Power | 35 to 49 dBmV | 30 to 55 dBmV | Outside 25-55 dBmV |
| SNR (Signal-to-Noise) | Above 33 dB | 30-33 dB | Below 30 dB |
| Corrected/Uncorrected Errors | 0 or very low | Low, not increasing | Rapidly increasing |
If your signal levels are outside the acceptable range, the issue is with your cable line, not your modem or router. This could be a damaged coaxial cable, a bad splitter, corrosion on connectors, or a problem at the ISP's end. Share these numbers with your ISP's tech support — they'll understand immediately what the issue is.