Arcadyan KVD21 Gateway

Find technical details, tutorial links, and other information about your Arcadyan KVD21 gateway.

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Meet your Arcadyan KVD21 Gateway

For more gateway steps, such as instructions on how to install your SIM or reset your gateway, check out our Tutorials. 


Front view of the Sagemcom Fast 5688W gateway


An image of the back of the Sagemcom gateway with arrows pointing to it's parts. In the middle of the gateway is the Label. Below that is the Data Port. Below the Data Port are two Ethernet Ports. Below the Ethernet Ports is the Power Button. Below the Power Button is the Power Port.

Reading the gateway label

The label on the back of your gateway includes information about the device and network. 

The default Wi-Fi network name and Wi-Fi password can be found below the IMEI barcode.

Arcadyan KVD21 Gateway Label with an outline around the Wi-Fi name and password in the top-left corner

Need help setting up your gateway or changing your default Wi-Fi name and password?

LCD Screen

Press the left or right arrow ( < or > ) on the LCD panel with your finger to move between screens. The illuminated dot on the bottom of the screen indicates where you are in the screen sequence.


  • The gateway displays up to five bars, indicating signal strength. 
  • The number of bars shown represents the strength of the gateway's current connection to the cellular network.
  • An 'X' indicates the gateway is not connected to the cellular network.


  • The number displayed indicates the number of devices currently connected to the gateway (including wireless and wired devices).
  • Use the T-Mobile Internet app to see and manage each connected device.

Internet Line Number

The Internet Line Number screen displays your internet number, which can be used to identify your account when calling for support and making payments online.

Language Settings

The gateway supports both English and Spanish on the LCD screen. To adjust this setting:

  1. From the Languages screen, select Change
  2. Select English or Espanol.
  3. Press (OK) button to set the language.


The Messages screen allows you to view your messages by pressing < and > to scroll between messages. 

To delete a message:

  1. Press O (OK) on the panel to select VIEW MESSAGES and view unread messages.
  2. Select NEXT to read the next message.
  3. Select DONE when you have read all messages.
  4. Select DELETE to delete a message.
  5. When prompted with a message asking you to confirm deletion, select YES to confirm.

You can block messages to your gateway through your T-Mobile account. See Message Blocking for details.


Notifications can appear at any time during gateway operation. Some are in response to an action you have taken, and others are related to network connection. 

Tech Specs

Technical details of the Arcadyan KVD21 Gateway



AC Adapter

100V - 240V

12V / 1.2A

Dimensions (W x H)

4.73 x 7.52 in (120mm x 191mm)

Operating temperature range

0° – 40° C (0° F – 104° F)


  • Dual Band Wi-Fi 6 (802.11ax) with 4x4MIMO
  • WPA2/WPA3 Wi-Fi Security
  • Ethernet plugs 2xRJ-45
  • USB Type C x 1 for regular power source
  • USB Type C x 1 for data (not functional)
  • Maximum recommended devices: 64


  • 5G bands: N41, N66, N71
  • 4G LTE bands: B2, B4, B5, B12, B41, B46, B66, B71

Firmware updates

  • Firmware updates are pushed out automatically when available. They can't be manually requested.
  • They're sent out in phases over a few weeks, so not all users get the update at the same time.
  • Updates happen between 1 am and 3 am PST; make sure your gateway is turned on during this time to get the update.
  • Do not restart the gateway when it’s updating. The gateway will automatically restart once the update is complete.

To check firmware version...

  1. From the T-Mobile Internet App, select MORE > Gateway information.
  2. Review the Firmware version.
Arcadyan KVD21 firmware version, fixes, and features
Firmware version Fixes & Features
  • Stability improvements
  • Internet Line Number added to gateway LCD
1.00.18 Security and stability improvements
1.00.16 Security and stability improvements
1.00.14 Release version


Web Gateway User Interface (GUI)

Access the Web GUI

You must disconnect active VPN sessions to connect and log in. 

  1. Power on your gateway and connect to it over Ethernet or Wi-Fi.
  2. Open a web browser and visit

Home screen

Check the Home screen to view the following information:

  • Connection status: Network status of the connected devices, the gateway, and the cellular network connection
  • Connection quality: Cellular strength, represented by the number of bars
  • Gateway information: Firmware version, serial number, and running time (time since the gateway was last restarted)
  • Mobile app: Scan the QR code with your smartphone to set up your gateway with the T-Mobile Internet app

Wi-Fi Networks

To configure your T-Mobile gateway with a single Wi-Fi network or two separate W-Fi networks, use the T-Mobile Home Internet app

Need help?

Our Troubleshooting guides can help fix the most common T-Mobile Internet issues, right from the comfort of your home!

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