1. Introducció
The ARRIS CM820A Cable Modem is designed to provide ultra-high-speed data access for cable service subscribers in both home and business environments. Utilizing DOCSIS 3.0 technology, this modem supports 8x4 bonded channels, enabling data services at speeds exceeding 300Mbps. It offers reliable and high-performance internet connectivity, making it suitable for advanced users and competitive against alternative broadband technologies.
2. Contingut del paquet
Verifiqueu que tots els elements siguin presents al paquet:
- ARRIS CM820A Cable Modem
- Adaptador d'alimentació
- Cable Ethernet
- Guia d'inici ràpid (no inclosa en aquest manual)
3. Producte acabatview
3.1 Indicadors del panell frontal
The front panel of the ARRIS CM820A features several LED indicators that provide status information about the modem's operation. Refer to the image below for the location of these indicators.

Figura 1: Frontal view of the ARRIS CM820A Cable Modem. Visible indicators include Power, DS (Downstream), US (Upstream), Online, and Link.
- Potència: Indica que el mòdem està rebent alimentació.
- DS (Downstream): Indicates downstream channel connectivity.
- US (Upstream): Indicates upstream channel connectivity.
- En línia: Indicates successful internet connection.
- Enllaç: Indicates an active Ethernet connection to a device.
3.2 Ports del panell posterior
The rear panel contains all the necessary ports for connecting the modem to your cable service and network devices.

Figura 2: posterior view of the ARRIS CM820A Cable Modem. Ports include a coaxial cable connector, an Ethernet port, and a power input.
- PERSUADIR: Connects to the cable wall outlet.
- ETHERNET: Es connecta a l'ordinador o al router mitjançant un cable Ethernet.
- POTÈNCIA: Es connecta a l'adaptador de corrent.
4. Instruccions de configuració
Follow these steps to set up your ARRIS CM820A Cable Modem:
- Connecteu el cable coaxial: Connect one end of the coaxial cable to the COAX port on the modem and the other end to a cable wall outlet. Ensure the connection is finger-tight.
- Connecteu el cable Ethernet: Connect one end of the Ethernet cable to the ETHERNET port on the modem and the other end to your computer's Ethernet port or to the WAN/Internet port of your router.
- Connecteu l'adaptador d'alimentació: Connect the power adapter to the POWER port on the modem and then plug the adapter into an electrical outlet.
- Encès: The modem will automatically power on. Observe the front panel LEDs. The Power, DS, US, and Online indicators should eventually become solid green, indicating a successful connection. This process may take several minutes.
- Activa el servei: Contact your Internet Service Provider (ISP) to activate your new modem. You will need to provide the MAC address of the modem, which is typically found on a label on the bottom or back of the device.
- Verifica la connexió: Once activated, open a web browser on your connected device and attempt to access a website to confirm internet connectivity.
5. Funcionament del mòdem
The ARRIS CM820A Cable Modem operates continuously once connected and activated. It functions as a bridge between your home network and your Internet Service Provider's network.
- Funcionament continu: For optimal performance, it is recommended to leave the modem powered on at all times.
- Llums indicadores: Monitor the front panel LEDs to quickly assess the modem's status. Solid green lights for Power, DS, US, and Online indicate normal operation.
- Dispositius de connexió: You can connect a single computer directly to the modem via Ethernet. For multiple devices or wireless connectivity, connect a router to the modem's Ethernet port.
6. Manteniment
Proper maintenance ensures the longevity and optimal performance of your cable modem.
- Ventilació: Ensure the modem is placed in a well-ventilated area to prevent overheating. Do not cover ventilation openings.
- Neteja: Clean the modem periodically with a soft, dry cloth. Avoid using liquid cleaners or aerosols.
- Cicle de potència: If you experience connectivity issues, a simple power cycle (unplugging the power adapter for 10-15 seconds and then plugging it back in) can often resolve minor problems.
- Connexions de cable: Periodically check that all cable connections (coaxial, Ethernet, power) are secure.
7. Solució De Problemes
This section addresses common issues you might encounter with your ARRIS CM820A Cable Modem.
7.1 Sense poder
- Símptoma: El LED d'alimentació està apagat.
- Solució: Ensure the power adapter is securely connected to the modem and a working electrical outlet. Try a different outlet.
7.2 Sense connexió a Internet
- Símptoma: Online LED is off or blinking.
- Solució:
- Verify coaxial cable connection to the wall outlet and modem.
- Power cycle the modem: unplug, wait 15 seconds, plug back in.
- Ensure your service is activated with your ISP.
- If using a router, power cycle the router as well.
- Contact your ISP if the issue persists.
7.3 Velocitat d'Internet lenta
- Símptoma: Internet speed is lower than expected.
- Solució:
- Power cycle the modem and any connected router.
- Assegureu-vos que tots els cables estiguin ben connectats.
- Temporarily connect a computer directly to the modem with an Ethernet cable to rule out router issues.
- Run a speed test. If speeds are consistently low, contact your ISP.
8. Especificacions
Key technical specifications for the ARRIS CM820A Cable Modem:
| Característica | Detall |
|---|---|
| Marca | ARRIS |
| Número de model | FBA_P-10-20521 |
| Versió DOCSIS | 3.0 |
| Vinculació de canals | 8x4 (Downstream x Upstream) |
| Tecnologia de connectivitat | Amb cable |
| Ports Ethernet | 1 port Ethernet Gigabit |
| Dimensions (LxWxH) | 7 x 7 x 2 polzades |
| Pes | 0.01 unces |
| Proveïdors d'Internet compatibles | Cox, Optimum, Spectrum, Xfinity (Compatibility may vary, confirm with ISP) |
9. Garantia i Suport
For warranty information and technical support, please refer to the documentation provided with your purchase or visit the official ARRIS weblloc. Els termes de la garantia solen cobrir els defectes de fabricació durant un període especificat a partir de la data de compra.
- Suport del fabricant: Contact ARRIS customer support for assistance with product issues, setup, or troubleshooting beyond this manual.
- ISP Support: For service activation, billing, or network-related issues, contact your Internet Service Provider directly.





