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Review of this 2.5G Multigigabit to USB C adapter

The main feature of this new USB Type-C or Thunderbolt 3 to Ethernet adapter, is that we have one 2.5G Multigigabit port, therefore, we can obtain a speed of up to 2.5Gbps in the local network, both in download and upload. Nowadays the vast majority of this type of adapters have Gigabit Ethernet speeds, therefore, we can transfer at a speed of approximately 115MB / s, however, with this device we can exceed the actual 230MB / s without any problem, both in download as upload.

This new adapter allows it to be connected to computers with both a USB Type-C port and also Thunderbolt 3, since both connections are compatible, therefore, we can use it both in Windows computers as also in macOS with Thunderbolt 3 connection. This new device, facing the RJ-45 port that it incorporates, has automatic speed detection, to always synchronize at the maximum possible speed of the link, you can synchronize at speeds of 2500Mbps / 1000Mbps / 100Mbps / 10Mbps, therefore, depending on the local network where we connect it, we will have one synchronization speed or another. Another very important feature is that it supports Full Duplex mode in both 2.5G and 1G, since it is a mandatory requirement of the standard, of course, we have MDI / MDI-X to detect crossed network cables and also work without problems.

On the front of the RJ-45 connector we will find two LED indicators To show us the status of the connection, we can see a green LED that will indicate that the synchronization works at 2.5Gbps, and an orange LED that will indicate that the synchronization works at 1Gbps. Another important detail is that does not require any kind of external power adapter, it is powered directly through the USB Type-C or Thunderbolt 3 port, in fact, the power consumption in operation is 250mA maximum, and the power consumption in standby is 60mA. D-Link has incorporated into this adapter a Energy saving system, because mainly this device will be used in battery powered laptops. Other important features of this device is that it supports the 802.1p standards for QoS, 802.1Q for VLANs, 802.1az for energy efficiency, and also the 802.3x protocol, which is flow control.

The connection cable has a length of 16cm, It is not too long, but it is enough so that it does not disturb if we want to connect a network cable in different positions. The D-Link DUB-E250 is really very small, with dimensions of 53 x 21.5 x 15mm, and a weight of only 28.5 grams, therefore, we can transport it in any pocket of the backpack where we have the PC.

Thanks to the use of this adapter, we will be able to transfer data at approximately 240MB / s, compared to the 115MB / s that the Gigabit Ethernet standard allows us. This means that we can transfer the same amount of information in half the time, therefore, if you are a graphic designer, video editor or want to make backup copies to a NAS server (with Multigigabit speeds and connected to a Multigigabit switch) you can squeeze the maximum 2.5G port.

External analysis

This USB Type C adapter (also compatible with Thunderbolt 3) to 2.5G Multigigabit Ethernet network port, comes in a small white and green box. On the front we will find the main characteristics of the equipment, such as that it is compact and portable to always carry it with us, it is up to 2.5 times faster than the popular Gigabit Ethernet standard, and also that it has support for Thunderbolt 3 in addition to USB type C, therefore, we can use it on both PC and MacOS.

On the back of the box we will find the main features in different languages, it indicates that it has 2.5G Ethernet connectivity, automatic speed detection and also LED indicators on the RJ-45 port to show us the status of the link synchronization. On the right side we can see the main specifications that we have already explained in the introduction, such as automatic speed detection, detection of crossed cables, supports Full-Duplex, does not require an additional power adapter, and is compatible with the Gigabit Ethernet standard and with its speed of 1Gbps, in addition to 100 / 10Mbps as well. Finally, we will need to install some drivers that are integrated into the device itself, so we will have to run the installer on our computer and we will have it installed and ready to go. On the left side we can see the minimum requirements of the USB type C to 2.5G Ethernet adapter, and that is that we will need a computer with Windows 7 or higher, or the operating system Mac OS 10.6 or higher, and we will also see the contents of the box.

Regarding the content of the box, we find the following:

  • D-Link DUB-E250
  • Quick install guide
  • Product guarantee.

The quick installation guide will tell us how we should connect this USB Type C adapter to a 2.5G Ethernet port, it will also tell us how we should install the drivers in Windows, which is simply by clicking on the new unit that the adapter itself generates.

The D-Link DUB-E250 adapter is a really small device, with dimensions of 53 x 21.5 x 15mm, and a weight of only 28.5 grams, in addition, the cable measures approximately 16 cm, ideal for connecting comfortably the Ethernet network cable.

View of the 2.5G D-Link DUB-E250 adapter in detail

At one end we will have the USB type C connector (also compatible with Thunderbolt 3), and at the other end we will have the RJ-45 connector with the typical green and orange status LEDs of the equipment that will show us the synchronization speed. If we have a synchronization of 2.5Gbps it will show it in green, if we have a synchronization of 1Gbps or less it will show it in orange.

On the back of the adapter we will have the exact model of the device, the hardware version, the serial number and also the MAC address of the adapter. Being an Ethernet network card, then logically we have a MAC address.

So far we have arrived with our external analysis of the device, as you can see, the most remarkable thing is the 2.5G Multigigabit port that this equipment incorporates, and also that we have compatibility with both USB type C and Thunderbolt 3 ports.

Test laboratory

The first thing we have done is connect this USB type C adapter to a 2.5G network port to an available port on our PC, specifically we have connected it to a rear USB type C 3.2 Gen 2 (at 10Gbps) port that our motherboard has, therefore, we can ensure that there is no type of bottleneck. As soon as we connect the device, we will get a new 1MB unit in “Equipment”. All we have to do is double click on this unit, execute with administrator permissions and in a few seconds we will have the Realtek driver installed to make it work, and this unit will disappear.

D-Link DUB-E250 Installation View on Windows

Once we install the drivers, we will have direct access to the wired network. As you can see, the synchronization speed is 2.5Gbps because we have used a Multigigabit switch. Depending on the switch and cabling, it will sync at the maximum speed of 2.5Gbps or at a lower speed.

D-Link DUB-E250 adapter sync view

Regarding the properties of the network card, it will indicate that the manufacturer is Realtek, and we can also access all the advanced options of the device to activate or deactivate functionalities. The most important thing that we should modify are the Jumbo frames, in our case, we have configured Jumbo Frames to 9K since it is compatible with the switch used.

We will also have the possibility to configure the priority and VLAN, the power consumption and other parameters that we should not touch, unless you know what you are doing. However, it is advisable to modify the Jumbo frame parameter to maximize the network at 2.5Gbps speed.

The speed that we obtain with this USB type C adapter to 2.5G Ethernet network port is the maximum that the interface provides us, as you can see in the following test with iperf 3. We have connected an iperf 3 server in a Multigigabit switch and this adapter as well, and we have achieved a speed of 2.46Gbps with Jumbo Frames at 9016 bytes:

In the case that you use a typical 1500-byte MTU, the maximum speed that you will obtain will be around 2Gbps approximately, we will not be able to squeeze the full potential of this device.

Regarding file transfer over LAN, having a Multigigabit speed, we must take into account several factors:

  • The equipment connected to the LAN must also have Multigigabit speed
  • The switch that joins all the equipment must be Multigigabit
  • SSDs must be used and not hard drives, otherwise, we will have a bottleneck.

The speed achieved in the transfer is 295MB / s, both in download and upload, since the network card is Full-Duplex.

As you have seen, we will achieve more than twice the real speed than if we used a Gigabit Ethernet connection, this is ideal for environments where we make backup copies or are going to transfer a large amount of data.


  • Compact and with a very elegant design
  • USB type C connector that today is the most used in laptops and ultrabooks.
  • Compatible with Thunderbolt 3 technology, ideal for Apple Macs
  • 2.5G Multigigabit network port, prepared for the new speeds of local networks.
  • Actual speed achieved by the DUB-E250 is 2.46Gbps, the highest possible and expected speed.
  • Price: outstanding, we can buy this device for about 60 euros.

Weak points

Last conclusions

This new USB Type-C adapter (also compatible with Thunderbolt 3) to 2.5G Multigigabit network port D-Link DUB-E250 is the perfect complement to your laptop or ultrabook. Normally, the latest models on the market do not have a native Ethernet port, because they do not physically fit in the laptop itself due to the thickness of the connector, having a USB to Ethernet adapter is very important to connect via cable to any local wired network. This model is compatible with both computers that have a USB Type-C port as well as Thunderbolt 3, ideal for use with Apple Mac computers that normally have this type of connectivity.

The speed achieved with the 2.5G Multigigabit port is the maximum that we will achieve, as long as we use Jumbo Frames at 9016 bytes, otherwise the maximum speed that we will achieve will be around the real 2Gbps, something completely normal and that we have previously verified in other cards network. Having the new connectivity with the NBASE-T standard is a point very in favor of this equipment, because we will be able to transfer data at more than twice the speed of the typical Gigabit Ethernet interface.

Regarding the price of about 60 euros, it is an expected price considering that Gigabit Ethernet adapters are around 30 euros approximately. For double the price you will have a little more than double the speed, and you will already be prepared for the speed of the LAN networks of the present and the nearest future.

Taking into account the technical characteristics of this USB Type-C adapter (also compatible with Thunderbolt 3) to 2.5G Multigigabit network port, the performance obtained in the tests and the price, RedesZone’s assessment is as follows:

We hope you liked the analysis of this new D-Link DUB-E250, if you have any questions you can put a comment and we will respond delightedly.