What to do if the Ethernet connection seems limited to 100 Mbps and you cannot exploit the potential of the connection ultrabroadband.

The speed of an Ethernet connection has increased, and by a lot, over the years. In March 2023 the inventor of Ethernet, Robert “Bob” Metcalfe was awarded the prestigious Turing Award. When Metcalfe introduced Ethernet in the early 70s, the bandwidth it was equal to about 2.9 Mbps (a huge amount for the time) when today it can even go up to 400 Gbps (Gigabits per second).

Because 100Mbps on the Ethernet connection can be limiting

Several have been presented and then approved over the years standard Ethernet increasingly performing. Today one speed limited to 100 Mbps on the computer’s ethernet card is often a major bottleneck not just because connectivity ultrabroadband optical fiber FTTH at 1, 2.5 or 10 Gbps is becoming more and more widespread also in Italy but also because, above all in the office and in the company, there is a need to transfer data at high speed even within the local network.

Think of a company within which they are installed NAS o servers that take care of data backup: backup copies of files and folders must flow quickly from one system to another and data transfers take place at the maximum speed possible. Also because, for example, the backup archives they are often heavy and it takes bandwidth to exchange data between one system and another within the LAN.

This is why the concept of Multigigabit Ethernet is gaining momentum.

List of Ethernet standards, at a glance

The main Ethernet standards, the achievable speeds and the introduction dates are listed below:

  • Ethernet 802.3 (10BASE5). Introduced in 1983, it was the first Ethernet standard for 10 Mbps data transmission over coaxial cable.
  • Fast Ethernet 802.3u (100BASE-TX). Launched in 1995, it allowed data transmission at 100 Mbps over UTP cable (unshielded twisted pair).
  • Gigabit Ethernet 802.3z (1000BASE-X). Introduced in 1998, this standard allowed data transmission at 1 Gbps over fiber optic cables or category 5 or higher UTP cables.
  • 10 Gigabit Ethernet 802.3ae (10GBASE-X). Dating back to 2002, this standard introduced 10 Gbps data transmission over fiber and copper cables.

  • 40 Gigabit Ethernet 802.3ba (40GBASE-X). Introduced in 2010, it allowed data transmission at 40 Gbps.
  • 100 Gigabit Ethernet 802.3bj (100GBASE-X). In 2010, the standard underwent a further evolution allowing data transmission at 100 Gbps.
  • 400 Gigabit Ethernet 802.3bs (400GBASE-X). In 2017, it even went up to 400 Gbps: this is the latest and fastest Ethernet technology currently available.

We also mention the Power over Ethernet (PoE) standard: the 802.3af and 802.3at standards, introduced respectively in 2003 and 2009, allow power network devices such as IP phones, surveillance cameras and wireless access points using the Ethernet cable.

Check if the network card is limited to 100 Mbps in Windows

To check if your system, connected to the switch or directly to the router, is limited to 100 Mbps, just press the key combination Windows+R then type ncpa.cpl.

In the window Network connections you must double-click on the icon corresponding to the Ethernet interface in use: in the latest versions of Windows it is called Ethernet and immediately below it is displayed the name of the network card physically installed in the computer.

Speed ​​limited to 100 Mbps on Ethernet connection: how to fix

Next to Speedit reads the maximum bandwidth that the network interface and therefore the Ethernet card installed in the system can manage; in the example 1 Gbps. Conversely, if the valore 100 Mbps it means that data transfers are somewhat limited.

Speed ​​limited to 100 Mbps on Ethernet connection: how to fix

As we have seen above, the spec Fast Ethernet o 100BASE-TX it was introduced in the mid-1990s as an evolution of the original 10 Mbps Ethernet. Nowadays, the use of this standard can be a significant limiting factor.

Because the network card transfers data at a maximum of 100 Mbps

There could be several reasons why your network card transfers data at 100 Mbps even if you have, for example, a connection ultrabroadband a 1 Gbps:

Your network card may be limited to a maximum speed of 100 Mbps

If you have an old network card, it may not support data transfer rates higher than 100 Mbps (it is not compatible with the latest Ethernet standards).

The advice is to press the key combination Windows+Xto select Device managementclick on Network cards then twice on the name of the detected network adapter on the screen Network connectionspreviously.

Speed ​​limited to 100 Mbps on Ethernet connection: how to fix

It is important to choose the correct network card because, for example, they may also be in the list virtual boards from virtualization solutions or locally installed VPN clients.

In the tab Advancethe option Gigabit automatic disable must be set to Disabled While Speed ​​and duplex are Auto Negotiation however verifying what is the maximum speed shown in the list.

Speed ​​limited to 100 Mbps on Ethernet connection: how to fix

For example, if only the voice were included 100 Mbps Full Duplexit means that the network card does not support le Gigabit Ethernet connection.

The suggestion is to try update the driver of the network card by first checking the specifications of the same (by examining the abbreviation printed on the chip of the card or looking for the specific model, you can ascertain whether or not it supports the GbE connections).

Alternatively, where possible, the replacement of this card with a more recent and more performing model can be evaluated.

The network cable you use to connect your computer to the network may not support speeds higher than 100 Mbps

Since your Ethernet card supports data transfer rates greater than 100 Mbps, you must use a higher-grade network cable, such as a Cat 5e or Cat 6 cable to connect the computer with the switch or router.

In the article on choosing ethernet cables and the differences between one and the other, we have clarified why a Cat 5 cable does not allow you to exceed 100 Mbps.

Even though the Ethernet cable is high speed, a defective RJ-45 connector or incorrectly wired can cause data rates to drop to 100 Mbps. And so even if the cable is capable of supporting higher speeds: 1 Gbps or more.

If one or more of the RJ-45 connector contacts are not connected properly or do not make good contact, the electrical signal carried over the Ethernet cable may be disturbed or attenuated during transmission.

Most modern network cards and Ethernet devices are designed to automatically detect the maximum speed they support and adjust data transfer accordingly. If the electrical signal is disturbed or attenuated due to a faulty connector, the network card or device may automatically reduce the transmission speed to ensure signal quality: this behavior can cause the data transfer speed to drop to 100 Mbps .

Your router or switch may limit your connection speed to 100 Mbps

In addition to the single computer’s network card and the connecting Ethernet cable, the third important variable is the LAN port to which the device is connected on the router or network switch.

Older devices may limit the speed to 100 Mbps, so it is important to check that the ports on your router are Gigabit Ethernet or even 2.5 GbE o 10 GbE if the network card and downstream cable support those speeds. The capabilities of each port are usually indicated on the router or switch. Furthermore, many network devices indicate with a differently colored LED when, due to the Ethernet cable used or the specifications of the downstream card, a Gigabit Ethernet data transfer cannot be activated.

It must be said however that regardless of the theoretically available bandwidth, everything has a overhead and the expected speed is never the one actually detected. Intensive data transfers in progress on the local network or from and to the Internet can also negatively affect the performance measured on individual devices in the LAN.

A speed test helps to check the performance during data transfer (download, upload and latency) but it is still possible to use a free program like LAN Speed Test to check the speed of the Ethernet and WiFi connection within the local network.

It is thus possible to understand if the bottleneck is the Internet connection or the configuration of the local network as a whole, the use of specific devices and network cables or the single Ethernet card on some devices.


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