T-Mobile High Speed 5G Internet Gateway (Arcadyan KVD21) External Antenna Guide


Looking to get the best possible data rates from your T-Mobile 5G Internet Gateway?

You’ll want to purchase and connect external MIMO antennas to the device’s internal U.FL ports.

In this guide, we'll:

  • Recommend the best external antennas to use.
  • Show you how to access the internal U.FL antenna ports, and how to install adapters for external antennas.
  • Explain how to aim the antennas for the best results.

Got T-Mobile's previous, cylindrical hotspot with the display on the top? Check out our guide for that device here.

In this guide

Important Note: To connect external antennas you'll need to open your T-Mobile Gateway. Read our instructions for doing so carefully to avoid damaging the device. Gateways are owned by T-Mobile, and they may charge you a repair fee if you return a damaged gateway device.

The Best External Antennas For the T-Mobile 5G Internet Gateway

Using a MIMO antenna outside your building, pointed at the nearest tower, can help you get the fastest 4G LTE and 5G data rates possible.

The T-Mobile 5G Internet Gateway has four internal U.FL ports, which allow for a 4x4 MIMO antenna system to be connected to the device.

Since 4x4 MIMO offers superior performance and since a 2x2 MIMO antenna would require you to choose a pair of the four ports to use (which can be a time consuming process), we highly recommend a 4x4 MIMO antenna over a 2x2 MIMO antenna.

Accessing the antenna ports does require some disassembly and we recommend being careful: If you damage the device and then later return it, T-Mobile may charge you a damage fee. Our instructions below guide you through how to connect and test antennas without damaging the device.

We recommend two different 4x4 MIMO antenna options for use with the T-Mobile 5G Internet Gateway:

Best for most users

This MIMO panel antenna kit will provide the best possible data rates, even if you're surrounded by trees, hills, or tall buildings. Ideal for band n41.

For most users, the best external antenna choice for the T-Mobile 5G Internet Gateway is our 4x4 MIMO Panel Antenna Kit. This antenna doesn’t require line-of-sight to the tower.

However, if you're connecting on T-Mobile's band 12 or band 71, then you'll usually be able to use a 2x2 MIMO Antenna Kit and still get good enough performance at a much lower cost.

Budget option, trickier to setup

This 2x2 MIMO panel antenna kit is a great budget option that'll provide a meaningful performance boost, especially on T-Mobile's low-frequency bands. Ideal for bands B12 and n71.

The 2x2 kit can actually be slightly more tricky to set up, as you'll need to be careful about which antenna ports you connect to on the router. We'll go into detail on this in our instructions below.

Why External Antennas Are Critical for Improving Data Rates

There's one big misconception about external antennas.

Most people think that external antennas primarily help you increase your data rates by increasing the signal strength.

But that's not the case.

An increase in signal strength is actually probably the third most important way that external antennas help.

Here are the three main ways that external antennas help you increase your data rates:

1.They Improve Signal Quality

In 4G LTE and 5G networks, signal quality is measured as SINR (Signal to Interference plus Noise Ratio) or sometimes as RSRQ (Reference Signal Received Quality).

Improving signal quality has a huge impact on your data rates.

Higher data rates allow your hotspot to communicate using "higher order modulation schemes." That means they can use the same wireless spectrum to send more data per second.

However, there's one big caveat:

In order to improve your signal quality, you need to both aim and shield your outdoor antenna properly. We talk more about this in the next section.

2.They Allow You To Connect On More Bands

Hotspots like the T-Mobile 5G Internet Gateway support a feature called "carrier aggregation."

Carrier aggregation allows the Gateway to connect on multiple cellular bands simultaneously.

The more bands you're connected on, the greater the bandwidth, and the higher your data rates.

However, many of the higher frequency bands aren't able to penetrate into buildings. Using external antennas allows you to access higher frequency bands, which are often less congested and offer higher speeds than lower frequency bands.

3.They Increase Your Signal Strength

As you might expect, using outdoor directional antennas can help increase the signal strength.

This helps increase data rates, but only up to a point.

If your signal strength (called "RSRP" in 4G and 5G networks) is stronger than about -100 dBm, stronger signal won't speed up your connection any further.

Installing External Antennas to the T-Mobile 5G Internet Gateway

Before getting started, it's always a good idea to run a couple of speed tests indoors from a device connected to your Gateway's WiFi. The results will fluctuate a little, but this is the baseline you're trying to improve.

Once you've tested your baseline internet speeds, you're ready to install external antennas. The T-Mobile 5G Internet Gateway doesn't have any external antenna ports, but it's possible to access the internal ports and install adapters that allow you to connect antennas.

In the next section of this guide, we'll show you how to open up your Gateway, connect adapters for external antennas, and close it back up.

Before you get started, you will need the following:

  • A small phillips-head screwdriver
  • A thin prying tool or flat-head screwdriver
  • Needle-nose pliers or tweezers
  • Two or four U.FL to SMA-Female pigtail adapters (included in our 2x2 and 4x4 External Antenna kits, respectively)
  • A secure container to keep screws and small parts safe while you work
Important note:

Be careful not to damage your T-Mobile Home Internet Gateway while disassembling.

As part of your agreement with T-Mobile, you "borrow" this equipment from them. When you end your service, you'll likely need to return the gateway to T-Mobile. If there's damage to the device they are contractually able to charge you up to $370 in damage fees.

Waveform does not make any guarantees nor take any responsibility for damage caused to your unit when following these instructions. Please proceed at your own risk.

If you do decide to return your unit to T-Mobile, make sure to reconnect the existing internal antenna connectors before doing so.

Step-by-Step Guide to Installing Adapters for External Antennas

Step 1: Power off the T-Mobile 5G Internet Gateway and unplug the power cable.

Step 2: After partially peeling away the sticker on the back of the device, unscrew the unhidden phillips-head screw.

Unscrew the phillips-head screw underneath the QR-code sticker.

Step 3: Remove the four circular rubber feet on the bottom of the Gateway.

Step 4: Unscrew the four unhidden phillips-head screws securing the bottom cover to the main housing.

Unscrew the four phillips-head screws from the bottom cover

Step 5: Using a flat-head screwdriver underneath each corner of the cover, apply pressure outwards to gently unlatch each one of the four corners.

Gently pry off each of the four corners of the top cover.

Step 6: Remove the two phillips-head screws located below the top cover.

Remove the two phillips-head screws securing the outer covers to the inner unit

Step 7: Starting from the bottom of the device, slowly unlatch the two halves of the outer cover by going along the length of the device with a flat-head screwdriver.

Use a flat head screwdriver to prying off the outer covers from the inner unit.

Step 8: Once both sides are fully unlatched, remove both halves of the outer covers by sliding them off and revealing the inner unit. As shown below:

This is the inner unit with outer covers removed

Step 9: Located behind the display screen, there will be a series of white cables connected to the circuit board by small U.Fl connectors for ports labelled M1, M2, D, and M.

These are ports M1, M2, D, and M.

Depending on which MIMO Antenna kit you own (2x2 or 4x4), two or four of these U.Fl connectors will need to be disconnected. Very carefully disconnect the cables using a prying tool or a pair of tweezers and following these guidelines:

  • If you have a 4x4 MIMO Antenna Kit, disconnect the cables for all of these ports.
  • If you have a 2x2 MIMO Antenna Kit, disconnect the cables for ports M and D, but leave ports M1 and M2 connected internally.

Be very careful here. U.Fl connectors can be quite fragile. Make sure you're very gentle to avoid breaking the connector.

Step 10: Install the U.FL to SMA-Female pigtail adapters by very carefully aligning and pressing them down into the ports you opened up in step 9. A quiet "click" can often be heard once the connectors are pressed down and fully connected.

Install the U.FL-male to N-female pigtail adapters into the ports you opened up in step 10

Step 11: Route your pigtail adapters through any one of the set of vents located on the top of the removed outer casing.

*Note: Try to route the pigtails through the vents such that they will be near the ports on the device once re-assembled to avoid any sharp bends and excessive force.

Route your pigtail adapters through the vent ports on one of the outer covers.

Step 12: Reassemble everything in reverse order.

Reassemble the gateway

Your T-Mobile 5G Internet Gateway should now be fully re-assembled, with the pigtail adapters protruding from the top.

You will connect your external antennas to the SMA-Female ends of the adapters your installed in your Gateway.

Positioning and Aiming MIMO Antennas

Positioning and aiming MIMO antennas well is crucial to getting the best performance to your T-Mobile 5G Internet Gateway, or indeed any other hotspot.

We've actually compiled a detailed instruction manual to accompany our own MIMO Antenna Kits, where we go into depth on the best ways to aim the antennas.

The goal is to find the best location and direction for the antenna(s), to maximize data rates to the T-Mobile Gateway. It can take a little patience, but can have a huge impact – it’s worth a bit of extra effort!

Connect your MIMO external antennas to your modified T-Mobile 5G Internet Gateway via the newly installed pigtail adapters, and go outside with your "test-rig".

With each location and direction you try, run a couple speed tests, and make a note of the results. Here are all the locations and directions where we recommend testing your MIMO antenna:

Where to test your signal

Where to test your signal

Pro tip: Don’t just go to the highest point of the roof! While signal is generally stronger the higher you go, there’s also often more interference. We’ve found it’s often better to mount the antenna(s) on the side of the building where the structure can shield the antennas from interference.

Once you've found the position which gets you the highest data rates to the T-Mobile Gateway, that's where you'll want to install the MIMO antenna. Go ahead and mount the antenna, run cables inside, connect everything up, and enjoy superior data rates!

T-Mobile 5G Internet Gateway Technical Specifications

Supported T-Mobile bands in the US

  • 5G Bands: n25, n41, n66, n71
  • 4G LTE Bands: B2, B4, B5, B12, B41, B46, B66, B71

Cellular Modem

  • Model: MediaTek T750 ARM Cortex-A55
  • MIMO Support: 4x4 w/ internal antennas or external antennas
  • Carrier Aggregation: Yes (2x 5G 40 MHz bands, 5x LTE 20 MHz bands)
  • LTE Performance Category: Cat 20
  • Max Theoretical Speeds: 2.5 Gbps Download, 316 Mbps Upload


  • Technologies: 802.11 ax
  • Bands: Simultaneous 2.4 GHz and 5 GHz


  • Cellular Antenna Ports: 6x internal U.FL
  • Ethernet Ports: 2x Gigabit RF-45 LAN Ports
  • Other Ports: 1x USB-C LAN port (not functional), 1x USB-C Power Delivery Port

Antenna Port Functions

  • Port M:
    • Frequency Range: 617-2690 MHz
    • Band Support (Download):
      • 4G: B2, B4, B5, B7, B12, B13, B14, B17, B25, B30, B41, B66, B71
      • 5G: n2, n25, n41, n66, n71
    • Band Support (Upload):
      • 4G: B2, B4, B5, B7, B12, B13, B14, B17, B25, B30, B41, B66, B71
      • 5G: n2, n25, n41, n66, n71
  • Port M1:
    • Frequency Range: 1710-5925 MHz
    • Band Support (Download):
      • 4G: B2, B4, B7, B25, B30, B41, B48, B66
      • 5G: n2, n25, n41, n66
    • Band Support (Upload):
      • 4G: B41
      • 5G: n41
  • Port M2:
    • Frequency Range: 1930-5925 MHz
    • Band Support (Download):
      • 4G: B2, B4, B7, B25, B30, B41, B48, B66
      • 5G: n2, n25, n41, n66
  • Port D:
    • Frequency Range: 617-2690 MHz
    • Band Support (Download):
      • 4G: B2, B4, B5, B7, B12, B13, B14, B17, B25, B30, B41, B66, B71
      • 5G: n2, n25, n41, n66, n71

Other Helpful Resources

A helpful guide on installing and maintaining U.FL connectors

T-Mobile's support page for the High-Speed 5G Internet Gateway


A helpful video of disassembling the T-Mobile Gateway by Nater Tater