1. Introduction
The Zoom Model 5345 is a high-performance DOCSIS 3.0 cable modem designed to provide fast and reliable internet connectivity. This modem supports speeds up to 343 Mbps and is certified by major cable service providers, allowing users to avoid monthly modem rental fees. Its 8x4 channel bonding ensures efficient data transfer, making it suitable for various internet usage needs.
2. Package Contents
Verify that all items are present in the package:
- Zoom 8x4 Cable Modem (Model 5345)
- Power Cube (AC Adapter)
- Ethernet Cable
- Quick Start Flyer
3. Setup and Installation
Follow these steps to set up your Zoom Model 5345 cable modem:
- Connect the Coaxial Cable: Connect one end of a coaxial cable (not included) to the cable wall outlet and the other end to the Cable port on the back of your Zoom modem. Ensure the connection is finger-tight.
- Connect the Ethernet Cable: Connect one end of the supplied Ethernet cable to the LAN port on the back of your Zoom modem. Connect the other end to the Ethernet port on your computer or router.
- Connect the Power Adapter: Plug the power cube into the Power port on the back of the modem, then plug the other end into an electrical outlet.
- Power On: The modem will automatically power on. Allow a few minutes for the modem to establish a connection with your cable service provider. The front panel lights will indicate connection status.
- Activate Your Service:
- Open a web browser on the computer connected to the modem.
- You may be redirected to your cable service provider's activation page. Follow the on-screen instructions.
- If not redirected, contact your cable service provider's customer support. You will need to provide the modem's MAC address (CM MAC), which is located on a sticker on the bottom or back of the modem.

Figure 1: Front and side view of the Zoom 8x4 Cable Modem Model 5345, showing the indicator lights and ventilation.
4. Operating Indicators
The front panel LEDs provide information about the modem's operational status:
| Indicator | Status | Description |
|---|---|---|
| Power | Solid Green | The modem is powered on. |
| DS (Downstream) | Solid Green | Modem is connected to the downstream channel. |
| Flashing Green | Scanning for a downstream channel. | |
| US (Upstream) | Solid Green | Modem is connected to the upstream channel. |
| Flashing Green | Scanning for an upstream channel. | |
| Online | Solid Green | Modem is online and ready for internet traffic. |
| Flashing Green | Establishing IP connectivity. | |
| LAN | Solid Green | Ethernet connection is active. |
| Flashing Green | Data is being transmitted or received over the Ethernet connection. |
5. Maintenance
To ensure optimal performance and longevity of your modem:
- Keep the modem in a well-ventilated area to prevent overheating.
- Avoid placing the modem near heat sources or in direct sunlight.
- Clean the exterior with a soft, dry cloth. Do not use liquid cleaners or aerosols.
- Periodically check cable connections to ensure they are secure.
- If experiencing connectivity issues, try power cycling the modem by unplugging it from the power outlet for 10 seconds and then plugging it back in.
6. Troubleshooting
Common issues and their solutions:
- No Internet Connection:
- Check all cable connections (coaxial, Ethernet, power) to ensure they are secure.
- Verify that the Power, DS, US, and Online lights are solid green. If not, refer to the "Operating Indicators" section.
- Power cycle the modem by unplugging it for 10 seconds and plugging it back in.
- Contact your cable service provider to confirm service status and modem activation.
- Slow Internet Speed:
- Ensure your computer or router is connected to the modem with a Gigabit Ethernet cable (Cat5e or Cat6 recommended).
- Perform a speed test to verify your actual internet speed.
- Temporarily disconnect other devices from your network to see if performance improves.
- Contact your cable service provider to check for network issues in your area or to confirm your subscribed speed plan.
- Modem Lights Not On:
- Ensure the power adapter is securely connected to the modem and a working electrical outlet.
- Try a different electrical outlet.
7. Specifications
| Feature | Detail |
|---|---|
| Model Number | 5345 |
| DOCSIS Standard | 3.0 (Backward compatible with 2.0, 1.1) |
| Channel Bonding | 8 Downstream x 4 Upstream |
| Max Downstream Speed | 343 Mbps |
| Ethernet Port | 1 Gigabit (10/100/1000 Mbps) |
| IPv6 Support | Yes |
| Dimensions (LxWxH) | 4.1 x 1.6 x 5.7 inches |
| Weight | 1 pound |
| Color | Black |
| Power Input | 12 Volts |
| Operating System Compatibility | Windows, Macintosh (via Ethernet) |
| Certified by | Comcast XFINITY, Time Warner Cable, Charter Spectrum, and other leading service providers. |

Figure 2: Dimensions of the Zoom 8x4 Cable Modem Model 5345.
8. Warranty and Support
The Zoom Model 5345 cable modem is covered by a two-year warranty provided by Zoom Telephonics. For technical support or warranty claims, please contact Zoom Telephonics directly. Contact information can typically be found on the manufacturer's website or the Quick Start Flyer included with your product.
For additional resources, you may refer to the official User Guide PDF available online: Zoom 5345 User Guide (PDF)





