Users regularly ask what exactly the cable connecting a router to a computer or the one coming into their apartment from their internet service provider is called. It's often mistakenly referred to as a "USB cable" or simply a "network cord," which leads to confusion when purchasing equipment or ordering service from an internet service provider. The correct technical name for this component is twisted pair (Twisted Pair), and this is the term you should use if you want to be understood at an electronics store or by tech support.
Externally, this cable is a flexible wire with a diameter of approximately 5-6 millimeters, inside which are hidden several pairs of copper strands twisted together at a specific frequency. This twisting is not random: it minimizes electromagnetic interference and crosstalk between adjacent pairs, ensuring stable data transmission at high speeds. The ends of this wire are usually equipped with plastic connectors of the type RJ-45, which visually resemble an enlarged telephone handset connector, but have 8 contacts instead of two or four.
Understanding what is in front of you twisted pairUsing a dedicated Ethernet cable, not a standard power cord or USB cable, is critical for properly setting up a home network. Using an inappropriate cable, such as a phone or USB extension cable, will prevent a connection, as the physical signal structure and pinouts are completely different. In this article, we'll take a detailed look at cable design, its speed categories, and help you choose the best option for your equipment.
⚠️ Attention: Don't attempt to connect your ISP's cable directly to a USB port on your computer without a special adapter. Ethernet and USB signal structures are incompatible, and such an error could damage your network card or router port.
Correct name and design of the cable
The official name of the cable used to build local area networks (LANs) is twisted pairThis name derives from the conductor's design: inside the outer insulation are four pairs of copper strands, each twisted around another pair with a different twist pitch. This design feature effectively combats external electromagnetic interference and reduces mutual interference between pairs, which is especially important when transmitting high-frequency signals.
There are two main types of twisted pair cable construction that you will find commercially available. The first type is UTP (Unshielded Twisted Pair), which stands for unshielded twisted pair. This is the most common option for home use, and it doesn't have an additional metal shield around the wires. The second type is FTP or STP (shielded versions), which have a foil or mesh braid along the entire length of the cable to protect against strong industrial interference.
To connect to the router and computer, a connector is installed at the ends of the cable. RJ-45 (Registered Jack). It's important not to confuse it with the smaller RJ-11 telephone jack. Although they look similar, it's possible to insert a telephone connector into a network port, but this can cause mechanical damage to the contacts inside the router's socket due to differences in geometry.
The difference between an Ethernet cable, a USB cable, and a telephone cable
One of the most common mistakes beginners make is trying to use a USB cable instead of a network cable. Visually, the connectors may look similar to a non-technical user, but functionally, they are completely different interfaces. Ethernet (network cable) is designed to transmit data between network devices using TCP/IP protocols, whereas USB (Universal Serial Bus) is used to connect peripherals to a computer and has different operating logic and voltage.
A telephone cable, which is often confused with a network cable due to the similarity of the connectors, usually has 2 or 4 contacts, while the full functionality of the modern Internet requires 8 contacts in the connector. RJ-45If you try to plug a telephone cable into the router's WAN port, there will be no connection because the wrong pairs of contacts are physically connected to transmit a digital signal.
Key differences to help you identify the right cable:
- 🔌 Connector: The network cable has an RJ-45 connector (wide, 8 contacts), USB has a rectangular or oval (Type-C), and the telephone cable has a narrow RJ-11 connector.
- 📏 Thickness: Twisted pair cable is typically thicker and stiffer than USB cable due to its four pairs of twisted wires and thick insulation.
- 🏷️ Marking: The jacket of a network cable almost always contains text indicating the category (for example, Cat5e) and the type of cable (UTP/FTP).
Using the wrong type of cable will not only be ineffective, but can also be dangerous. For example, some older telephone lines can carry ringing voltage, which could theoretically damage the sensitive electronics of the network port, even though modern routers have protection. Therefore, always check the markings on the cable itself before connecting.
⚠️ Attention: If you see a transparent connector on the cable with eight colored wires running all the way to the end, it's a twisted pair cable. If there are two or four thin wires, it's most likely a telephone cable, which isn't suitable for internet use.
Twisted pair categories: Cat5e, Cat6 and speed
Not all twisted pair cables are created equal. They are divided into categories that determine the maximum signal frequency and, consequently, network throughput. For home users, the three most important categories are those found in stores and when connected by a service provider.
The most common standard today is Cat5e (Category 5 enhanced). This cable supports speeds of up to 1 Gbps at distances of up to 100 meters and frequencies of up to 100 MHz. The vast majority of apartments and offices use this type, as it offers the best price-performance ratio for providers offering speeds up to 1 Gbps.
More modern standards such as Cat6 And Cat6a, are designed for speeds up to 10 Gbps. They have thicker insulation and are often equipped with a central plastic crosspiece separating the pairs of wires, improving performance at high frequencies. However, if your router and provider plan don't support speeds above 1 Gbps, paying extra for Cat6 cables doesn't make sense.
| Cable category | Maximum speed | Frequency band | Application |
|---|---|---|---|
| Cat5 | 100 Mbps | 100 MHz | An obsolete standard, rarely encountered. |
| Cat5e | 1 Gbps | 100 MHz | Standard for home and office (basic) |
| Cat6 | 10 Gbps (up to 55 m) | 250 MHz | Server rooms, new buildings, gigabit networks |
| Cat6a | 10 Gbps (up to 100 m) | 500 MHz | Backbone networks, data centers |
When choosing a cable, it's important to remember that the speed of the entire network is limited by the weakest link. If you install the ideal cable at home, Cat6aIf your router is old and only has 100 Mbps ports, you won't get speeds higher than 100 Mbps. Therefore, before purchasing an expensive cable, check the port specifications of your equipment.
Cable construction: shielded or not
When choosing a cable for your router, you may come across abbreviations UTP And FTPThey indicate the presence or absence of a shield, which protects internal wires from external interference. Understanding the difference will help you avoid overpaying for unnecessary features or, conversely, ensure stability in challenging conditions.
UTP (Unshielded Twisted Pair) is a standard cable used in 90% of indoor applications. It's flexible, lightweight, and inexpensive. This type is more than adequate for indoor installations where there are no strong sources of electromagnetic radiation near the cable.
FTP (Foil Twisted Pair) or STP (Shielded Twisted Pair) cables have an additional shield made of foil or metal mesh. These cables are necessary if the wire is laid parallel to power lines, near powerful electric motors, in industrial facilities, or outdoors where lightning strikes are possible. The shield must be grounded at both ends, otherwise it acts as an antenna, collecting interference.
It's also worth mentioning the core material. High-quality cables use pure copper (marked Cu). However, there are many cheap analogues with copper-plated aluminum on the market (marking CCA — Copper Coated Aluminum). Aluminum conductors are more brittle and have lower electrical resistance, which is critical for long cable runs (over 30-40 meters) and PoE technology (powering devices over cable).
⚠️ Attention: If you plan to use PoE technology (for example, to connect an IP camera or access point), strictly avoid cables with aluminum conductors (CCA). Aluminum has a high resistance and can burn out under load, de-energizing the equipment.
How to connect a cable to a router: instructions
Connecting a cable to a router is simple, but requires care to avoid mixing up the ports. On the back of any router, there are a group of Ethernet (LAN) ports and one dedicated port (WAN or Internet), which is often colored differently (blue, yellow, or red).
The cable from the provider (Internet to the apartment) must be inserted into the port WAN (or Internet). The cable going to your computer, laptop, or TV is inserted into any of the ports LAN (Local Area Network). You can mix them up, and the connector will physically connect, but the internet won't work because the signal from the provider won't reach the correct router logic.
Procedure:
- 🔌 Find the port labeled as
WANorInternet, and connect the cable from the provider there until you hear a characteristic click. - 💻 Take the second cable (patch cord) and connect the port
LAN 1(or any other LAN) on the router with the computer's network card. - 💡 Check the indicators: the LED next to the LAN port should light up or blink, indicating a physical connection.
☑️ Checking the cable connection
After physical connection, the operating system usually detects the network automatically. If this doesn't happen, you may need to configure PPPoE, L2TP, or a static IP address in the router's web interface, but the cable itself must be connected correctly.
What should I do if the LAN indicator is not on?
If the indicator doesn't light when you connect the cable, try replacing the cable with a known-good one. The connector may be damaged or the wire may be broken. Also, check whether the network card is enabled in the BIOS or the drivers are installed in the OS.
Common problems and their solutions
Even with the right cable, connection issues can still occur. One of the most common is damage to the conductors inside the insulation. Twisted pair cables don't like being bent sharply, especially at sharp angles, or pinched by doors or baseboards. If the cable is pinched, connection speeds can drop from 1 Gbps to 100 Mbps or even disappear completely.
Another problem is oxidation of the contacts in the connector. RJ-45If the router is placed on the floor or in a dusty area, dust may accumulate in the port, causing an unstable connection. In such cases, gently cleaning the port with compressed air or reconnecting the cable (removing it and reinserting it until it clicks into place) can help.
Cable length is also worth considering. The Ethernet standard guarantees stable operation at distances of up to 100 meters. However, with cheap cables made of aluminum conductors, the actual range may be no more than 40-50 meters. If you need to extend internet to a remote corner of your property or a large house, it's better to use fiber optics or Wi-Fi bridges, as long copper cables may not be able to handle gigabit speeds.
It's important to remember speed compatibility. If you connect a modern gigabit router to an older computer whose network card only supports 100 Mbps, the connection will be established, but it will operate at the speed of the older device. In this case, upgrading to a more expensive cable (Cat6) won't speed up the internet, as the limitation is in the computer's hardware.
Is it possible to extend a router cable by twisting it?
Manually twisting twisted pair cables ("twisting") is strictly prohibited. This will disrupt the characteristic impedance and lead to signal loss, especially at high speeds. To extend the cable, use special extension connectors (RJ-45 couplers) or purchase a ready-made patch cord of the required length.
Does cable color affect internet speed?
No, the color of the outer jacket (white, black, blue) is purely for marketing and design purposes. The color of the insulation has no effect on data transfer speed or quality. Only the cable category (Cat5e/6) and the core material are important.
Do I need to change my cable if I upgrade to a faster plan?
If your current cable is rated Cat5e (as indicated on the cable jacket), it supports speeds up to 1 Gbps. If your new plan doesn't exceed this speed, you don't need to upgrade. If your plan exceeds 1 Gbps, you'll need a Cat6 cable and a compatible router.
Why does the cable get hot?
The data cable itself shouldn't get hot. If you feel heat at the connection point, this could indicate a poor connection, corrosion, or, in rare cases, a short circuit if the cable is damaged and touching the power supply. In this case, it's best to replace the cable.
Can you use a telephone cable for internet?
A standard telephone cable (2 conductors) won't work with modern Ethernet. However, ADSL technology does use the telephone line, but it requires a special modem (DSL) rather than a standard router with a WAN port. A twisted pair cable (8 conductors) is required to connect the router.