Can an Ethernet Cable Slow Your Internet Speed?

Can an ethernet cable slow internet speed title picture

Did you know that an ethernet cable can drastically slow your internet speed?

Ethernet cables are often an overlooked aspect of a home network. Many people use them every day without thinking about them. This is dangerous, because ethernet cables can have a direct affect on their internet speed.

If an ethernet cable is not rated to support the speed of an internet plan, it will slow down the internet speed of the network. To ensure that ethernet cables are not limiting the internet speed of a network, it is extremely important that they are designed to support speeds faster than the internet plan in place.

Granted, ethernet cables can be confusing because they come in a variety of types and categories, but it’s important to know that some are better than others depending upon what you’re using them for.

The good news for you? We’re going to take a deep dive into the different types of ethernet cables. Not only that, but I’ll detail what these cables are used for and how you can tell what type you’re using.

What Do Ethernet Cables Look Like?

Does this look familiar?

CAT5e Ethernet Cable
A CAT5e Ethernet Cable

The above picture is a CAT5e ethernet cable. The other end of the cable looks identical to the end you see here (which is a male RJ45 connector). As you’ll find out, the vast majority of ethernet cables will look like this.

Now that we know what these cables look like, let’s dig deeper to find out what they’re used for.

What Do Ethernet Cables Do?

Ethernet cables are used to connect computers to the internet with a wired connection.

Additionally, ethernet cables can be used for communication between computers and other devices such as printers and fax machines. They’re also used to connect your modem to your router (if they’re separate devices). To provide a visual of what a home network might look like:

Home Network Ethernet Cable Diagram Example

As you can see, ethernet cables can be used for a majority of the devices in your home.

Why Should Ethernet Cables Be Used?

Ethernet connections offer a more reliable connection than if you were to wirelessly connect your devices.

Wireless connections (i.e. WiFi) are subject to interference that ethernet connections don’t experience (e.g. walls, other electronic devices using the same radio channel, etc.). In fact, your internet connection will be faster over ethernet than if you were to use a wireless connection.

But only if you use the right cables.

I know what you are thinking:

What’s the big deal? It’s just a cable. How can it play such a big factor in my internet speed?

How Can an Ethernet Cable Slow Your Internet Speed?

As of this writing, ethernet cable speeds of up to 10 Gbps can be expected, while the newest versions of WiFi can only offer maximum speeds of 867 Mbps (802.11ac) and 150 Mbps (802.11n). That’s a significant difference.

It’s important to note here that simply using ethernet cables will not result in 10 Gbps internet. You need to make sure you have the proper internet equipment in your home. You also need to make sure you’re getting sufficient bandwidth from your Internet Service Provider (ISP).

The most important aspect of ethernet cables is you need to make sure they’re not the bottleneck of your network.

What do I mean by this?

What Is an Example That Will Help Me Visualize This?

Picture your home internet like a system of water pipes. If the water flow from the street is 20 gallons/minute but your pipes can only handle 5 gallons/minute of water, your shower will only receive 5 gallons/minute of water. The pipes in this example are your ethernet cables, and your shower is your device (laptop, smart TV, etc.)

Perhaps a diagram will help you visualize this:

Ethernet Cable Restricting Data Rate Example
Pipes can restrict the flow of water

The point here is that if you’re paying for gigabit internet (1 Gbps) but your ethernet cables can only support 10 Mbps, your device will only have access to 10 Mbps. You can’t force data through the cables faster than what they’re designed for.

Let’s use the water piping example again. If the flow of water from the street is 5 gallons/minute and your pipes are able to handle 20 gallons/minute of water flow, your shower will only have 5 gallons/minute of water flow.

Ethernet Cable Not Increasing Data Rate Example
Pipes don’t make the flow of water faster

The pipes don’t increase the flow of water. If you want to optimize the flow of water to your shower, the pipes in your house need to be designed for the flow of water coming from the street.

How Does This Apply to Ethernet Cables?

The same is true for ethernet cables. You need to ensure they can support the bandwidth (i.e. speed) that’s being provided to you by the ISP. Ethernet cables don’t make your internet faster, but they sure can slow it down if the wrong cables are used.

Make sense?

In order to determine what speeds your ethernet cables need to support, you need to look at:

  • The speed of the internet plan that you’re signed up for
  • The bandwidth supported by delivery devices in your home network (e.g. modem and router)
  • The bandwidth needed for your devices to function properly (e.g. smart T.V., laptop, etc.)

I will make this process very easy for you, but first let’s take a look at the types of cables available:

Ethernet Cable Category Comparison

Types of Ethernet Cables

There are multiple categories of ethernet cables. Some categories are no longer used and as a result I’ll only go over them briefly. The categories you should pay attention to are the ones that are in use today, and the ones that will be used in the future.

Let’s get started:

Category 1 (CAT1)

CAT1 ethernet cables are no longer used. They were previously installed in analog telephone wire installations prior to 1983. At the time, they were only designed to carry voice communications. This makes them unusable in computer networking applications.

What’s more, the organizations that establish the standards for the ethernet cable categories (TIA/EIA) do not officially recognize CAT1 cables.

Should I Use CAT1 Cables in My Network?

No. This above background is merely for your information. You will not need to use CAT1 cables in your internet network. In fact, I will be shocked if you come across CAT1 ethernet cables in your travels.

Category 2 (CAT2)

CAT2 ethernet cables are an improvement over CAT1 cables, but only marginally.

Unlike CAT1 ethernet cables, CAT2 cables are designed for computer networking and digital voice communication. The bad news is they support very low speeds (up to 4 Mbps) for computer communication. This is molasses in today’s world.

Similar to CAT1 cables, the TIA/EIA did not establish standards for CAT2 cables as an official ethernet category.

Should I Use CAT2 Cables in My Network?

No. As you can guess, these cables are no longer used for networking. However, you may still be able to find them in some (really) old telephone systems today.

Category 3 (CAT3)

CAT3 cables were introduced in the early 1990s and were widely used in local area networks (LANs). In simpler terms, CAT3 cables were used to connect computers and devices to allow for communication between them.

They enabled data transmission rates up to 10 Mbps, which was more than double what CAT2 cables could provide. The speed of CAT3 cables was a big improvement at the time, but their dominance was short lived; in the mid 1990s superior cables were developed and CAT3 cables were replaced.

CAT3 cables are recognized by TIA/EIA as an official ethernet cable category. They were the first category of ethernet cable that the group developed standards for.

Should I Use CAT3 Cables in My Network?

No. Although these cables were improvements over the ones that came before them, you won’t see them in use today. 10 Mbps won’t support the speeds required in today’s world.

Category 4 (CAT4)

Although category 4 cables were developed for computer communications, they ended up being used more in telecom-based communications.

They supported faster speeds than CAT3 cables (up to 16 Mbps) but never gained traction in the computer networking world. As a result, you’ll only find them in very old communications systems that haven’t been recently upgraded.

Although CAT3 cables were recognized by TIA/EIA as an official category of ethernet cables, CAT4 cables were not.

Should I Use CAT4 Cables in My Network?

No. You’ll very likely never cross paths with CAT4 cables, and there are much better options available to you. Even if they were widely used, you wouldn’t want to use them because you’ll need data rates faster than 16 Mbps.

Category 5 (CAT5)

When CAT5 cables were developed, they were a huge upgrade over previous ethernet cables. They support speeds up to 100 Mbps. This was a huge upgrade in performance at the time.

Unlike CAT4 cables, they were widely used for computer communication in the 1990s. They were developed for telephone and video signals as well, but they were mostly used for computer networks.

TIA/EIA recognized CAT5 cables as an official category, although they published a newer CAT5 standard in 2001.

Should I Use CAT5 Cables in My Network?

Most likely not. As I’m sure you can guess, better performing ethernet cables have been developed and CAT5 cables have mostly been replaced as a result. Although 100 Mbps isn’t horrible, you can find cheap alternatives that provide significantly higher performance. I would advise you to use better cables in your network.

Category 5e (CAT5e)

As mentioned in the previous section, the CAT5e standard was developed in 2001 to provide improvements to CAT5 cables. This category of cable provides performance improvements over CAT5 cables, as well as faster data rates. CAT5 cables had issues with crosstalk, which is caused by the alignment of the wires within the ethernet cable. Crosstalk was minimized by twisting the wire pairs within the cables, which we’ll get to later.

CAT5e cables enable data rates of up to 1,000 Mbps (1 Gbps).

Should I Use CAT5e Cables in My Network?

Yes. Now we’re talking. 1,000 Mbps is a sufficient data rate for many home networks, even if you have fiber internet. This is widely used in many businesses and home internet setups, and will be a good option for most people. I use CAT5e cables in my home network, as well as CAT6 cables (read on!).

Category 6 (CAT6)

CAT6 ethernet cables take CAT5e cables to another level. Similar to CAT5e cables they’re assembled to minimize any crosstalk interference that may occur by twisting the cable pairs. To further reduce interference, CAT6 ethernet cables have two mechanisms for providing additional insulation to the cables:

  • Including an insulating spline in the center of the cable to further separate each individual wire
  • Providing foil shielding for each individual pair of twisted wires in the cable

Here’s a picture of the shielding inside a CAT6 cable:

Shielded ethernet cable inside

Category 6 cables are rated for speeds up to 10 Gbps at short distances, so they’re faster than CAT5 cables as well.

Many datacenters, government websites, and hospitals utilize CAT6 cables as a result of their massive data transfer needs.

TIA/EIA has developed the standards for CAT6 cables and recognize it as an official category of ethernet cable.

Should I Use CAT6 Cables in My Network?

Yes. CAT6 cables enable data speeds that’re most likely more than what you’d need at home. That being said, they’re not extremely expensive. They will allow you to “future proof” your internet because internet speeds will continue to increase in the future and you know you won’t have to replace your ethernet cables when that happens. I have some CAT6 cables in my home network for this reason.

In short, you can’t go wrong using these cables for your network as long as you are willing to spend some extra money for them.

Category 6A (CAT6A)

CAT6A cables take CAT6 cables a step further. The “A” in CAT6A stands for “augmented” as they’re an improvement over CAT6 cables. The differences between CAT6 and CAT6A are as follows:

  • CAT6A cables support the same data rates as CAT6 (up to 10 Gbps), but over longer distances (up to 100 meters). CAT6 cables support 10 Gbps up to 55 meters.
  • CAT6A cables are built to tighter specifications than CAT6 cables. This further prevents potential crosstalk in the wires.
  • CAT6A cables are thicker than CAT6 cables, which makes them less flexible. Less flexible cables makes it harder to install them in tight spaces (like offices). It also makes CAT6A cables more expensive to install than CAT6 cables.

TIA/EIA revised the CAT6 cable standard in 2008, leading to the introduction of CAT6A.

Should I Use CAT6a Cables in My Network?

Most likely not. If you’re setting up a home network or small office, CAT6A will probably be overkill. In most recreational cases you won’t need ethernet cables longer than 55 meters.

This is the reason why I use CAT6 cables in my home network and not CAT6A; I only need about 10 feet of ethernet cable and CAT6 cable supports the same data rates. There was no reason for me to spend the extra money on CAT6A cables.

Category 7 (CAT7)

You may think that Category 7 cables are an improvement over CAT6A cables, but it’s actually the opposite. The standard for CAT7 cables was developed in 2002 (before CAT6A standards were established).

CAT7 cables were developed as a standard by a group of companies, and not by TIA/EIA like most other cables. As a result, there are several differences between CAT7 cables and CAT6:

  • These cables don’t use the traditional RJ45 connector that most other cables use. CAT7 cables use the GG45 connector which isn’t backwards compatible with RJ45 connectors
  • They have stricter specification requirements for limiting crosstalk
  • They enable the same data rates as CAT6 cables (up to 10 Gbps) but for up to 100 meters

The IT industry didn’t widely adopt CAT7 cables because of their GG45 connectors. The TIA/EIA developed CAT6A standards to account for this.

What is an RJ45 Connector?

For your reference, this is what an RJ45 connector looks like:

Ethernet Cable with RJ45 Connector
RJ45 Connector

CAT6A cables provided the same performance specifications as CAT7 cables but they used RJ45 connectors. In addition, the IT community felt more comfortable with CAT6A cables because TIA/EIA signed off on them as an approved ethernet cable standard. As a result CAT6A cables were widely adopted and CAT7 cables were not.

Should I Use CAT7 Cables in My Network?

No. Don’t let the fact the fact that CAT7 seems better or newer than CAT6A fool you. If you need high data rates in your network over a long distance (up to 100 meters), go with CAT6A cables. You’ll want the same connector on all your ethernet cables for simplicity.

That being said, CAT6A/CAT7 specifications will be overkill in most applications.

Category 8 (CAT8)

CAT8 cables enable the fastest data rates. They can support speeds up to 40 Gbps for up to 30 meters. Although they’re faster than all other cables, they support data rates over shorter distances.

They’re an IEEE standard (not TIA/EIA) that uses RJ45 connectors like most other cables. They’re designed for use in datacenters as a result of the data rates they support. The cables are configured to almost eliminate crosstalk. Their configuration makes them the hardest to install in tight spaces because they aren’t flexible.

Should I Use CAT8 Cables in My Network?

No, unless you’re looking to configure a data center. CAT8 cables are mostly used between switches in datacenters, which can’t afford interference. This type of cable won’t be your best choice in any other application.

Ethernet Cable Configurations

When looking to buy ethernet cables, you’ll most likely see the terms “twisted pair”, “untwisted pair”, “shielded”, and “unshielded”. It’s important to know the differences between the performance of these configurations.

Untwisted Pair Cable

In all ethernet cables used today (CAT5 and above), the wires in an ethernet cable are twisted. This helps reduce interference between the wires in the cable. Each wire has electricity running through it, which creates a magnetic field in the cable and can interrupt the electric signals in the other wires next to it.

To visualize this, look at the image below. In an untwisted pair configuration, the pairs of wires blue-white, orange-white, etc. wouldn’t be twisted together. They would simply be side-by-side within the cable.

You won’t see untwisted cables used today so this is just for informational purposes.

Twisted Pair Cable

In twisted pair cables, each pair of wires in an ethernet cable is twisted. This is what it looks like inside the cable:

Picture of an Unshielded Twisted Pair Ethernet Cable (with sheath removed)
Unshielded Twisted Pair Ethernet Cable (sheath removed)

As you can see, the pairs of orange-white, green-white, brown-white, and blue-white are twisted within the ethernet cable.

Twisted pair cables will experience less crosstalk interference and therefore better performance. The twists in the wire pairs ensure that the electromagnetic forces in the twisted wires don’t affect the other pairs in the cable.

Any ethernet cable you purchase today will be twisted pair assuming it’s CAT5 or above.

When it comes to twisted pair cables, there are 2 types: shielded twisted pair (STP) and unshielded twisted pair (UTP)

Shielded Twisted Pair (STP) Cable

Some ethernet cables have a layer of foil wrapped around all the pairs of cables inside it. Looking at the picture above, you can see a foil wrapper around all the twisted pairs.

The purpose of the shield is to prevent interference from the electric fields of nearby electronic devices (or the other wires in the cable). This will improve performance, but it comes with a few drawbacks:

  • It’s more expensive than unshielded cable
  • It’s less flexible than shielded cable
  • If there are no other electronic devices around causing interference, it’s slower than unshielded cable

Shielded cables are best used in datacenters and other applications where they’ll be close to other electronic devices or cables.

Unshielded Twisted Pair (UTP) Cable

Ethernet cables that are unshielded do not have foil around the pairs of twisted wires.

Picture of Unshielded CAT5e Cable
Unshielded CAT5e Cable

As you can see, there are only twisted pairs of wires in the sheath.

In contrast to shielded cables, unshielded cables:

  • Are cheaper
  • Are more flexible
  • Can be faster than shielded cables if there is no nearby electronic interference

In most home applications and offices (outside of the server room/datacenter), you’ll probably be fine with unshielded cables.

How Do I Know What Ethernet Cable I Have?

It’s impossible to tell what kind of cables you have just by looking at their appearance.

For example, look at this picture:

CAT5e vs. CAT6 Ethernet Cable Side-by-side Comparison
CAT5e vs. CAT6 Ethernet Cable

One of the cables is CAT5e and the other is CAT6. Can you tell which one is which?

The answer is no.

Thankfully, the ethernet cables have labels printed on their side to help identify them.

CAT5e Cable Labeling
CAT5e Cable Labeling

As you can see, the above cable is a CAT5e cable. What’s more, you can see that the wires inside the cable are unshielded twisted pairs (UTP).

I recommend you double check all the ethernet cables in your network so you know what you have. This will give you an idea of what you need to replace as well.

Does Ethernet Cable Length Affect Internet Speed?

Most of the time, the answer is no.

In most cases you won’t experience any loss in speed or reliability based upon the length of ethernet cable you get. You’ll only have to worry about this if you are installing a network in a large office building where cables are longer than 100 meters.

This application is not the case for the majority of people. If you’re looking to install longer runs of cable, it’ll be best to use CAT6A cables (if they fit your data rate requirements).

What Ethernet Cables Should I Get?

My advice with ethernet cables would be to air on the side of caution.

For example if you have a home internet plan with the following:

  • 100 Mbps from the internet service provider
  • A modem rated for 100 Mbps (or greater)
  • A router rated for 100 Mbps (or greater)
  • You’ll only need shorter ethernet cables for your setup (less than 55 meters)

You should get either CAT5e or CAT6 cables.

Could CAT5 cables provide you with the speed you need? Most likely.

Would they allow you to upgrade your internet plan at any time as they get faster and cheaper? No.

If you have a fiber internet plan with the following:

  • 1,000 Mbps from the internet service provider
  • A modem rated for 1,000 Mbps (or greater)
  • A router rated for 1,000 Mbps (or greater)
  • You will only need shorter ethernet cables for your setup (less than 55 meters)

You should get either CAT5e or CAT6 cables.

CAT5e and CAT6 cables are pretty cheap compared to your internet plan. You should make sure you build in room to upgrade your internet without having to buy new cables as well.

This’ll ensure that your often-overlooked ethernet cables aren’t the bottleneck of your internet connection. Let other people deal with that problem.

If you’re looking to buy ethernet cables, I’d recommend these Cat5e cables, or these Cat6 cables. You can get them in a variety of lengths and colors depending upon your home internet setup.

Wrap Up

As always, feel free to reach out to me via the Contact Me page or the comments section below if you have any questions or you would like to share your experience.

If you would like to learn more about how other aspects of your home network could affect your internet speed, check out our other posts on this topic:

Does Your Modem Affect Your Internet Speed?

Does a Router Affect Your WiFi Speed?

Is an Ethernet Cable Faster than WiFi?

Does an Old Computer Affect Your Internet Speed?

Does Ethernet Cable Length Affect Network Speed?

Ross Ricky

Ross Ricky is an engineer and cybersecurity professional who wants nothing more than for you to get the most out of your home network.

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