The Arris SURFboard S33 is a DOCSIS 3.1 multi-gigabit cable modem built for high-speed cable internet plans. It is a modem only, which means it does not broadcast Wi-Fi and does not act as a router. To get Wi-Fi in your home, you connect the S33 to a separate wireless router or mesh system. This manual covers setup, activation, what the status light colors mean, admin login, Wi-Fi and bridge mode questions, the S33v2 and S33v3 versions, resets, and fixes for the issues S33 owners run into most often.
The S33 is a modem only, so it needs a router or mesh system to create a wireless network. Pick up the piece you are missing and get whole-home coverage.
Features
The Arris SURFboard S33 was announced in late 2020 and remains one of the fastest modems in the SURFboard lineup. Its main features include:
- DOCSIS 3.1 technology, backward compatible with DOCSIS 3.0 networks.
- Support for cable plans up to 2.5 Gbps on a single device.
- One 2.5 Gbps Ethernet port plus one 1 Gbps Ethernet port.
- Combined throughput of up to 3.5 Gbps across both ports when your provider supplies a second IP address.
- IPv4 and IPv6 support.
- A single color-changing status light on the front instead of a row of separate lights.
- A compact, rounded white design intended to sit out in the open, which also helps it stay cool.
- Compatibility with Xfinity, Spectrum, Cox, and other major U.S. cable internet providers.
The S33 has no built-in Wi-Fi, no router, no MoCA networking, and no telephone (VoIP) support. It is designed to pair with a separate Wi-Fi router or mesh system. It is not compatible with DSL, fiber, or satellite services such as AT&T, CenturyLink, or Verizon Fios.
Specifications
| Device type | Cable modem (no Wi-Fi, no router) |
|---|---|
| DOCSIS version | DOCSIS 3.1, backward compatible with DOCSIS 3.0 |
| Channels | 2 x 2 OFDM DOCSIS 3.1 channels, 32 x 8 DOCSIS 3.0 bonded channels |
| Max plan speed | Up to 2.5 Gbps on a single connection |
| Combined throughput | Up to 3.5 Gbps across both ports (requires a second IP from your provider) |
| Ethernet ports | One 2.5 Gbps port, one 1 Gbps port |
| Link aggregation | Not supported (ports cannot be combined into one connection) |
| Status light | One multi-color LED bar under the SURFboard logo |
| IP support | IPv4 and IPv6 |
| Admin IP address | 192.168.100.1 |
| Hardware versions | S33, S33v2, S33v3 (same specifications) |
| Color | White |
| Compatible providers | Xfinity, Spectrum, Cox, and other major U.S. cable providers |
One detail worth understanding: the two Ethernet ports do not bond together. A single device or router can reach up to 2.5 Gbps through the 2.5 Gbps port. The second port serves a separate connection and needs a second public IP address from your provider, which is why the 3.5 Gbps figure refers to two combined connections rather than one fast link.
Provider notes
- Xfinity: the S33 is approved for Xfinity download tiers, including gigabit and faster plans. It is not on Xfinity's Next Gen Speed Tier list, so it will not deliver the faster upload speeds Xfinity offers in upgraded areas. If upload speed matters to you on Xfinity, see our Arris S33 vs S34 comparison.
- Spectrum: approved for plans up to 1 Gig, and Spectrum's list includes the S33v2 and S33v3 revisions.
- Cox: on Cox's compatible list, and the 2.5 Gbps port is useful on Cox's fastest tiers.
Provider lists change, so confirm the S33 against your provider's current approved modem page before you buy or activate. Deciding between models? Our Arris S33 vs SB8200 comparison covers who needs the 2.5 Gbps port and who does not.
S33 vs S33v2 vs S33v3
Arris has shipped the S33 in three hardware revisions: the original S33, the S33v2, and the S33v3. The version is usually not printed on the outside of the box. Look at the label on the bottom of the modem or the quick start guide inside the package.
According to Arris, every revision meets the same specification and there is no difference in performance. The ports, speeds, status light, and setup steps in this manual apply to all three. Two practical differences do come up:
- Activation: a provider's system may list the revisions separately. If an agent says the modem is not recognized, tell them the exact model on your label (for example, S33v2) and read them the HFC MAC ID.
- Admin password: newer units often use the last eight digits of the serial number instead of the word "password." See the Admin Login section.
Setup and Installation
Plan for about 10 to 15 minutes, plus activation time with your provider.
- Place the S33 near your cable outlet and your router, on a flat surface with open air around it.
- Connect the coaxial cable from the wall outlet to the coax port on the back of the modem. Hand tighten the connector until snug.
- Connect an Ethernet cable from the 2.5 Gbps port on the modem to the internet or WAN port on your router. For a single computer, you can connect directly to that computer instead.
- Plug the power adapter into the modem and then into a wall outlet. The modem powers on by itself, and the front light can take up to 15 seconds to appear.
- Wait for the front status light to stop blinking green and turn solid green or solid blue. This can take several minutes as the modem finds and locks onto your provider's signal.
- Once the light is solid, continue to activation below.
Which port should you use? Use the 2.5 Gbps port for your router in almost every case. It works fine with a router that only has a 1 Gbps WAN port, and it is ready if you upgrade later. For plans faster than 1 Gbps, use a Category 6 (Cat 6) or better Ethernet cable and a router with a 2.5 Gbps WAN port. Otherwise the connection tops out around 940 Mbps.
Activating With Your Provider
A new or transferred modem must be registered with your cable provider before it will pass internet traffic.
- Have your account details and the modem's serial number and HFC MAC ID ready. These are printed on the label on the bottom of the S33.
- Connect a device to the modem or router and open a web browser.
- Most providers redirect you to an activation page automatically. If not, use your provider's app or self-activation page. Xfinity customers can activate the S33 in the Xfinity app.
- Follow the prompts to link the S33 to your account. You can also call your provider and give them the modem's HFC MAC ID to activate it manually.
- The modem may restart once or twice during activation. Allow it to finish before testing your connection.
- Open any website to confirm you are online.
What the S33 Light Colors Mean
The S33 has one status light, a bar under the SURFboard logo on the front. It changes color and blink pattern to tell you what the modem is doing.
| Solid blue | Online in DOCSIS 3.1 mode. This is the fastest connection and the light most owners should see. |
|---|---|
| Solid green | Online in DOCSIS 3.0 mode. Your internet works normally. Some providers and areas connect this way. |
| Blinking green | Searching for downstream and upstream channels. Normal for a few minutes after power up. If it never stops, see Common Issues below. |
| Solid amber | Power is on. You will see this briefly at startup. |
| Blinking amber | A firmware update is downloading. Do not unplug the modem. It will restart by itself when finished. |
| Alternating blue and green | Error mode. Power cycle the modem. If it returns, contact your provider or Arris support. |
| No light | No power. Check the power adapter, the outlet, and any power strip switch. |
Own a different SURFboard or want the full breakdown across models? See our Arris SURFboard modem lights guide.
How to Access the Admin Settings (192.168.100.1)
The S33 has a built-in web manager where you can view connection status, signal levels, the event log, and the firmware version.
- Connect a computer, phone, or tablet to the network that runs through the S33.
- Open a web browser and type 192.168.100.1 into the address bar, then press Enter.
- If a security warning appears, choose the option to continue to the page. The warning is expected, because the modem uses its own local certificate.
- On the login screen, enter the username admin. For the password, try password first. If that is rejected, enter the last eight digits of the serial number printed on the bottom label. Newer units, including many S33v2 and S33v3 modems, use the serial number method. The login is case sensitive.
- Select Apply or Login to open the web manager.
For security, change the default admin password after your first login and store the new one somewhere safe. If you are locked out, a factory reset restores the default login.
How to Change the Wi-Fi Name (SSID)
The S33 does not create a Wi-Fi network, so it has no SSID of its own. The Wi-Fi name comes from the router or mesh system connected to the modem. To change it:
- Find your router's admin address. Common addresses are 192.168.0.1 or 192.168.1.1, and it is often printed on the router label.
- Open that address in a browser and log in with your router's admin credentials.
- Open the wireless or Wi-Fi settings section.
- Find the network name or SSID field, enter your new name, and save.
- Reconnect your devices to the renamed network using the existing Wi-Fi password.
The exact menu names vary by router brand. The S33 itself does not need any changes for this.
How to Change the Wi-Fi Password
As with the network name, the Wi-Fi password lives on your router, not on the S33. To change it:
- Log in to your router's admin page using the address and credentials on its label.
- Open the wireless security or Wi-Fi settings section.
- Locate the password, passphrase, or pre-shared key field.
- Enter a new password. Use WPA2 or WPA3 security if your router offers it.
- Save the change, then reconnect each device with the new password.
If you also want to change the modem's admin password, that is a separate setting found at 192.168.100.1, covered in the Admin Login section above.
Bridge Mode
Many people search for how to set up bridge mode on the S33, so it is worth being clear: the S33 is a standalone modem and already operates as a straight pass-through. It does not have a router mode to turn off, so there is no separate bridge mode to enable.
This means:
- Your router handles all routing, Wi-Fi, and network address assignment.
- You do not get a double NAT issue from the S33 itself, because it is not routing.
- There is no bridge mode toggle to look for in the modem's settings.
Bridge mode is only relevant on combination modem and router units, where you switch off the router half. The S33 needs no such step. If you previously used a gateway with bridge mode and replaced it with the S33, you can simply connect your router and proceed normally.
Maintenance and Reset
Firmware updates
The S33 receives firmware updates from your cable provider over the network. There is no manual update button and no file to download, on any hardware version. Keeping the modem powered and connected lets it receive updates automatically. A blinking amber light means an update is in progress. You can see the current firmware version in the web manager at 192.168.100.1.
Restart (power cycle)
A restart fixes many temporary problems and keeps your settings intact.
- Unplug the modem's power adapter.
- Wait about 60 seconds.
- Plug it back in and wait for the status light to turn solid green or blue.
Restarting the router too? Our router restart guide covers the right order.
Factory reset
A factory reset returns the modem to default settings, including the admin login. Use this only if instructed by support, if you are locked out of the web manager, or after exhausting other steps.
- With the modem powered on, locate the recessed reset button on the back.
- Press and hold it with a paperclip for about 15 seconds, then release. A short press only restarts the modem.
- Wait for the modem to restart fully. You may need to contact your provider to re-establish service afterward.
Placement and heat
Like every DOCSIS 3.1 modem, the S33 runs warm. Keep it on a hard, flat surface with open air on all sides. Avoid closed cabinets, carpet, direct sun, and stacking it on top of a router or cable box.
Common Issues and Solutions
The light keeps blinking green
Blinking green means the modem is still searching for your provider's channels. Give it up to 10 minutes after power up. If it never turns solid, check that the coax cable is hand tight at both the wall and the modem, remove any unnecessary splitters, and try a different coax outlet if you have one. Then power cycle the modem. If the blinking continues, the cause is almost always a signal problem, an outage, or a modem that has not been activated, all of which your provider can check from their end.
The light is green instead of blue
Solid green is a working connection in DOCSIS 3.0 mode, so there is nothing to fix if your speeds match your plan. If you pay for a gigabit or faster plan and speeds are low, ask your provider whether DOCSIS 3.1 is active in your area and have them check your signal levels.
The light alternates blue and green
This is the S33's error pattern. Unplug the modem for 60 seconds and plug it back in. If the pattern returns, try a factory reset. If it still returns, contact your provider or Arris support, since this can point to a provisioning or hardware problem.
No internet even though the light is solid
A solid light with no internet usually points to the router or to activation. Connect a computer directly to the modem's 2.5 Gbps port and restart the modem. If that computer gets online, the issue is in your router. If it does not, contact your provider to confirm the modem is activated on your account.
Speeds are slower than my plan
Confirm you are using the 2.5 Gbps port with a Cat 6 or better cable, since older cables and the 1 Gbps port cap speeds at 1 Gbps. Test with a device connected directly to the modem to rule out the router or Wi-Fi. Remember that the S33 does not bond its two ports, so a single connection tops out at 2.5 Gbps.
Only getting about 940 Mbps on a faster plan
This points to the 1 Gbps port, an old cable, or a router with a 1 Gbps WAN port. Move your connection to the 2.5 Gbps port, use a Cat 6 or better cable, and confirm the connected device or router also supports 2.5 Gbps.
Upload speeds are lower than expected on Xfinity
The S33 is not on Xfinity's Next Gen Speed Tier list, so it stays on standard upload speeds even in areas where Xfinity has rolled out faster uploads. Downloads are unaffected. If faster uploads matter to you, our S33 vs S34 guide explains the upgrade path.
Connection drops randomly
Loose or low-quality coax connections are the most common cause. Re-seat the coax cable, remove extra splitters, and try a different coax outlet if available. Heat can also cause drops, so give the modem open air. If drops happen at the same times each day, ask your provider to check your signal levels and the line outside, since that pattern usually comes from the network rather than the modem.
The modem feels hot
Warm to the touch is normal. Hot enough to cause drops is not. Move the S33 out of any cabinet, off carpet, and away from other electronics, and keep it flat on its base with clear space around it.
Cannot reach 192.168.100.1
Make sure your device is connected through the S33 and not a separate network such as cellular data. Try a different browser or a private browsing window, and try typing https://192.168.100.1. If a router sits between you and the modem, you may need to connect a device directly to the modem to reach the page. A power cycle often restores access.
The default password does not work
Use the username admin with the last eight digits of the serial number from the bottom label as the password. If neither that nor "password" works, someone may have changed it. A factory reset restores the default.
Provider does not recognize the modem
Have the serial number and HFC MAC ID from the bottom label ready and confirm them with your provider. Give the agent the exact model on the label, including v2 or v3 if shown. Ensure your plan is a cable plan, since the S33 does not work with DSL, fiber, or satellite service.
General Troubleshooting Steps
When something is not working, work through these in order:
- Check the status light against the light table above to see what the modem is reporting.
- Power cycle the modem and your router, waiting a full minute before plugging each back in.
- Check every coax and Ethernet connection for a snug fit.
- Remove unnecessary coax splitters and test on a known good outlet.
- Test a device connected directly to the modem to separate modem issues from router or Wi-Fi issues.
- Verify the modem is activated and that there is no outage by checking with your provider.
- Review signal levels and the event log at 192.168.100.1, or ask your provider to read them remotely.
- As a last resort, perform a factory reset and re-activate with your provider.
Pair your S33 with the right router or mesh system for fast, reliable coverage in every room.
Frequently Asked Questions
Does the Arris S33 have Wi-Fi?
No. The S33 is a modem only. You connect it to a separate Wi-Fi router or mesh system to create a wireless network.
Is the Arris S33 a modem or a router?
It is a modem. It brings the internet signal in from the coax line and hands it to one device. A router shares that connection with everything else in your home.
What is the best router to pair with the Arris S33?
For plans up to 1 Gbps, any good gigabit router works. For plans faster than 1 Gbps, choose a router or mesh system with a 2.5 Gbps WAN port so the modem's fast port is put to use.
What is the default login for the S33?
The address is 192.168.100.1 and the username is admin. The password is either password or the last eight digits of the serial number, depending on the unit. Change it after your first login.
What does a blinking green light mean on the S33?
The modem is searching for your provider's signal. It is normal for a few minutes after startup. If it lasts longer than about 10 minutes, check the coax connection and contact your provider about signal or activation.
What is the difference between the S33 and the S33v2?
They are hardware revisions of the same modem with the same specifications. Arris states there is no performance difference. Newer revisions may use the serial number based admin password.
What is the difference between the S33 and the S34?
The two look the same and share the same ports and download speeds. The S34 adds support for faster upload tiers such as Xfinity's Next Gen speeds. Full details are in our S33 vs S34 comparison.
Does the S33 need bridge mode?
No. As a standalone modem, it already passes traffic straight through and has no router mode to disable.
Does the S33 support MoCA?
No. The S33 has no MoCA networking built in. If you use MoCA adapters on the same coax wiring, install a MoCA point-of-entry filter where the cable line enters your home.
How do I update the S33 firmware?
You do not. Your cable provider pushes firmware to the modem automatically, and there is no manual update option.
What internet plans does the S33 support?
It supports cable plans up to 2.5 Gbps on a single connection and works with major U.S. cable providers such as Xfinity, Spectrum, and Cox.
Why is my second Ethernet port not giving me more speed?
The two ports do not combine into one connection. The second port requires a separate IP address from your provider and serves a separate connection.
Is a refurbished Arris S33 a good buy?
Yes. A modem has no moving parts, and a tested unit performs the same as a new one on your provider's network. The S33 in our shop is tested by hand and comes with a 90-day warranty and 30-day returns.
