Ethernet (RJ-45) Cables - which network cable should you choose? Complete guide

2026-08-27

Although we live in the era of fast wireless Wi-Fi networks and 5G standards, a traditional wired connection still remains unrivaled. Ethernet cables are the absolute foundation of stable, fast, and secure access to the Internet and local LAN networks. Learn the most important parameters of network cables, their types, and find out which cable to choose for your home, office, or professional applications.

What are Ethernet cables and what are they used for?

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Ethernet cable (commonly called a twisted-pair cable or network cable) is a signal cable used to transmit data in the Ethernet network standard. It provides a physical connection between devices in LAN (Local Area Network) networks. It is usually terminated with a characteristic transparent RJ-45 plug.

Unlike Wi-Fi, a wired connection is characterized by:

Maximum stability: No susceptibility to interference caused by thick walls, other wireless devices, or microwaves.
Minimal latency (ping): A key parameter for gamers as well as video calls and 4K/8K quality streaming.
Full bandwidth: A properly selected cable delivers exactly the speed offered by your Internet provider, without losses resulting from distance from the router.

Where are Ethernet cables used?

The use of network cables is enormous - from simple home installations to powerful server rooms:

Home and office: Connecting a router to a desktop computer, laptop, game console (PS, Xbox), Smart TV, or network printer.
Smart Home infrastructure and monitoring: Connecting IP cameras, home automation control units, and video intercoms.
PoE (Power over Ethernet) power systems: Using an Ethernet cable to simultaneously transmit data and supply power to devices (e.g. Wi-Fi access points, cameras).
Industry and Data Center: Dedicated networks in server rooms, connecting switches, servers, and NAS network drives.

Ethernet cable construction - twisted-pair design

The name “twisted-pair cable” is not accidental. Inside the insulation there are 8 copper conductors (cores), which are twisted together into 4 pairs. Twisting the cores helps eliminate electromagnetic interference (so-called crosstalk).

Depending on their construction, cables are also divided into:

Solid: A single, hard copper wire in each core. Used in flush-mounted and surface-mounted installations in walls (for installation in sockets or patch panels).
Stranded: The core consists of many fine copper wires. The cable is flexible and resistant to bending, ideal for ready-made connection cables (patch cords) used at a desk.

Ethernet cable category (Cat) - Speed and Frequency

The cable category indicates what data transfer speed the cable is able to support over a given distance (standard up to 100 meters) and at what frequency it operates.

Category	Transfer speed	Frequency	Max. Length
Cat 1	up to 1 Mb/s	no spec.	-
Cat 2	up to 4 Mb/s	10 MHz	100 m
Cat 3	up to 10 Mb/s	16 MHz	100 m
Cat 4	up to 16 Mb/s	20 MHz	100 m
Cat 5	up to 100 Mb/s	100 MHz	100 m
Cat 5e	up to 1 Gb/s (1000 Mb/s)	100 MHz	100 m
Cat 6	up to 10 Gb/s (up to 55m) / 1 Gb/s	250 MHz	100 m
Cat 6a	up to 10 Gb/s	500 MHz	100 m
Cat 7	up to 10 Gb/s	600 MHz	100 m
Cat 7a	up to 10 Gb/s (optionally 40 Gb/s over 50m)	1000 MHz	100 m
Cat 8.1	up to 25 Gb/s / 40 Gb/s	2000 MHz	30 m
Cat 8.2	up to 25 Gb/s / 40 Gb/s	2000 MHz	30 m

Characteristics of the most popular categories:

Cat 5e: For years the most popular, inexpensive option. Still sufficient for Internet up to 1 Gb/s.
Cat 6 / Cat 6a: The golden mean and the best choice for years to come. Provides support for fast 2.5G, 5G, and 10G networks. Cat 6a has additional shielding that protects the signal very well against interference.
Cat 7 and Cat 8: Cables for special tasks. Thick, heavily shielded, used mainly where there is a very high density of electrical wires and server equipment.

Cable shielding - Types of shields (U/UTP, F/UTP, S/FTP)

Shielding is an additional layer (aluminum foil or wire braid) that protects the transmitted signal against external electromagnetic interference (e.g. 230V electrical cables running nearby).

Basic construction types:

U/UTP (Unshielded Twisted Pair) - Unshielded twisted-pair cable

No shields of any kind.

Features: Very flexible, inexpensive, easy to lay.
Application: Standard home connections where the cable does not run close to the electrical installation.

F/UTP (Foiled Twisted Pair) - Foiled twisted-pair cable

The entire cable (all 4 pairs together) is wrapped with one layer of foil.

Features: Good protection against basic interference.
Application: Offices, apartments with extensive installations.

S/FTP (Shielded/Foiled Twisted Pair) - Fully shielded twisted-pair cable

Each pair of wires has its own foil shield, and additionally the entire cable is wrapped with a mesh braid.

Features: Maximum protection against interference and crosstalk. The cable is stiffer and thicker.
Application: Server rooms, industry, professional flush-mounted installations (requires grounding).

FAQ

Is an unshielded network cable (U/UTP) sufficient for an apartment?

Yes, it is completely sufficient. Under standard home conditions, the level of electromagnetic interference is low enough that a U/UTP cable will easily provide full transfer speed and low latency. Shielding (F/UTP or S/FTP) is necessary mainly when the cable runs in one conduit or trunking directly next to 230V electrical cables over a long section, or in industrial installations and server rooms.

What is the difference between a straight-through cable and a crossover cable?

A straight-through cable has an identical order of cores in the plugs at both ends (usually according to the T568B standard) and is used to connect devices of different types, e.g. a computer to a router or switch. A crossover cable has the transmit and receive pairs swapped (T568A on one side, T568B on the other) and was formerly used to directly connect two computers without using a router.

Can an Ethernet cable be joined or extended with a barrel (coupler)?

Yes, this is possible using a dedicated RJ-45 coupler (so-called barrel). However, remember that every connection along the transmission path introduces minimal signal attenuation and a potential point of failure. For home use with standard Internet, a high-quality coupler (matched to the cable category) will work well. However, if you are planning a stable flush-mounted installation or joining cables in a wall, a much better solution is to use a junction box with LSA connectors or Keystone modules.

Can a damaged twisted-pair cable be soldered?

Physically yes, but from a networking point of view this is a highly inadvisable solution. Twisting the wire pairs at the proper angle inside the cable serves to reduce interference (so-called crosstalk). Cutting open the cable and soldering the cores destroys this geometry, which causes significant signal interference, loss of data packets, and a drastic drop in connection speed. If the cable has been damaged, it is much better to cut out the damaged section and connect the wires with a Keystone/LSA connector or simply replace the entire section.

Why does an Ethernet cable limit speed to 100 Mb/s instead of 1 Gb/s?

The most common cause is damage to one of the 8 cores inside the cable or an incorrectly crimped RJ-45 plug. Only 4 cores are used for Fast Ethernet transmission (100 Mb/s), whereas for Gigabit Ethernet transmission (1 Gb/s), proper operation of all 8 cores is absolutely necessary. Other reasons include using an outdated cable, a damaged or dirty RJ-45 port in the computer or router, and incorrect network card settings in the system.

Does bending or kinking a twisted-pair cable damage data transmission?

Definitely yes. Too tight a bend (exceeding the permissible bend radius, usually 4 times the cable diameter) or a kink may lead to microcracks in the copper cores or deformation of the internal pair structure. This results in increased interference, packet loss, higher ping, and in extreme cases complete loss of connection or limiting the speed to 100 Mb/s. During installation, avoid bending the cable at a right angle (90°).

Show more entries from August 2026

Ethernet (RJ-45) Cables - which network cable should you choose? Complete guide

What are Ethernet cables and what are they used for?

Where are Ethernet cables used?

Ethernet cable construction - twisted-pair design

Ethernet cable category (Cat) - Speed and Frequency

Characteristics of the most popular categories:

Cable shielding - Types of shields (U/UTP, F/UTP, S/FTP)

U/UTP (Unshielded Twisted Pair) - Unshielded twisted-pair cable

F/UTP (Foiled Twisted Pair) - Foiled twisted-pair cable

S/FTP (Shielded/Foiled Twisted Pair) - Fully shielded twisted-pair cable

FAQ

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