Building a reliable, high-speed Ethernet network requires more than just buying the most expensive cable. Your network is only as strong as its weakest link, and more often than not, that weak link is the RJ45 connector. Whether you are wiring a smart home, setting up a corporate server room, or simply trying to get the most out of your fiber-optic internet connection, understanding RJ45 connector types is critical. Choosing the wrong plug for your cable can result in packet loss, slow speeds, and frustrating connectivity issues. 

 

Key Takeaways 

  • Match Connectors to Cables: You must match your RJ45 connector to your cable category (e.g., use Cat6 connectors with Cat6 cable) to prevent performance bottlenecks. 
  • Speed Variations: Cat5e supports up to 1 Gbps, while Cat6 and Cat6a support up to 10 Gbps. The physical design of the connectors changes to accommodate thicker wires as speeds increase. 
  • Shielding Matters: Shielded (STP) RJ45 connectors feature a metal casing and are required in environments with high electromagnetic interference (EMI). Standard home networks generally only require Unshielded (UTP) connectors. 
  • Installation Style: Pass-through RJ45 connectors allow wires to exit the front of the plug before crimping, making them highly recommended for beginners to ensure correct wiring order. 

 

What is an RJ45 Connector? 

An RJ45 connector is the standard physical connector for terminating twisted-pair Ethernet cables. The "RJ" stands for Registered Jack, and the "45" refers to the specific standard number. 

Visually, it is the clear plastic plug at the end of an internet cable that snaps securely into a router, switch, or computer. Every standard RJ45 connector has 8 pins that connect to the 8 individual colour-coded wires inside an Ethernet cable (an 8P8C configuration). 

While all RJ45 plugs look virtually identical on the outside, their internal construction varies widely depending on the cable generation (category) they are designed to terminate. 

 

RJ45 Connector Types by Ethernet Category: Cat5e, Cat6, and Cat6a  

As internet speeds have evolved, so have Ethernet cables. The wires inside the cables have gotten thicker and more tightly twisted to handle higher frequencies. Consequently, the RJ45 connector had to evolve to accommodate these physical changes. 

 

Cat5e RJ45 Connectors 

Cat5e (Category 5 enhanced) is the most common and budget-friendly standard for basic networking. It supports speeds up to 1 Gigabit per second (Gbps) at a bandwidth of 100 MHz. 

The wires inside a Cat5e cable are relatively thin (usually 24 to 26 AWG). Because of this, a Cat5e RJ45 connector features a straight-line pin configuration. All eight wires lay flat side-by-side inside the plug. They are incredibly easy to terminate, making them popular for DIY home networking. 

 

Cat6 RJ45 Connectors 

Cat6 cables are designed for faster networks, supporting speeds up to 10 Gbps (up to 55 metres) at a bandwidth of 250 MHz. 

 

To handle this increased speed and reduce crosstalk (interference between the wires), Cat6 cables use thicker copper conductors (usually 23 AWG) and feature a plastic spline down the centre of the cable. Because the individual wires are thicker, they cannot always fit side-by-side in a flat line inside the plug. 

 

Therefore, Cat6 RJ45 connectors often use a staggered (or zig-zag) pin design. Wires are fed into the connector in an alternating up-and-down pattern. If you try to force thick Cat6 wires into a flat Cat5e connector, the wires will jam, and the crimp will likely fail. 

 

Cat6a RJ45 Connectors 

Cat6a (Category 6 augmented) is the gold standard for future-proofing networks. It supports full 10 Gbps speeds at a massive distance of 100 meters, utilizing a 500 MHz bandwidth. 

 

The wires inside a Cat6a cable are even thicker, and the overall cable jacket is incredibly robust. Cat6a RJ45 connectors are specifically engineered to handle this bulk. They feature wide conductor holes, a highly pronounced staggered pin layout, and often come in two-piece or three-piece designs. These multi-piece designs include a "load bar" (a small plastic guide) that helps align the thick wires before inserting them into the main connector housing. 

 

Shielded vs. Unshielded RJ45 Connectors 

Beyond the Category (Cat5e, Cat6, etc.), RJ45 connectors are divided into two main environmental types: Unshielded (UTP) and Shielded (STP). 

 

Unshielded (UTP) RJ45 Connectors 

Unshielded Twisted Pair (UTP) connectors are the industry standard for 90% of home and standard office environments. 

They are made entirely of a clear, heavy-duty plastic housing. Because standard homes and offices do not have severe electrical interference, plastic connectors are more than sufficient. They are cheaper, easier to crimp, and highly flexible. 

 

Shielded (STP) RJ45 Connectors 

Shielded Twisted Pair (STP) connectors are wrapped in a metal casing (usually nickel or tin-plated brass). 

These are required when running Ethernet cables through high electromagnetic interference (EMI) or radio frequency interference.  

 

Examples: radio frequency interference, machinery, server rooms with massive power supplies, or running cables parallel to electrical wiring in a wall. 

 

When you use a shielded Ethernet cable (which contains internal metal foil), you must use a shielded RJ45 connector. The metal casing of the connector touches the foil or "drain wire" of the cable, grounding the connection and discharging the electrical interference. If you use an unshielded connector on a shielded cable, the shielding becomes an antenna for interference, completely ruining network performance. 

 

Pass-Through vs. Standard RJ45 Connectors 

When shopping for an RJ45 connector, you will also need to choose between standard and pass-through designs. 

 

Standard RJ45 Connectors: The wires are pushed into the connector until they hit a plastic wall at the end. You must cut the wires to the exact perfect length before inserting them. If they are too short, the metal pins won't pierce the copper, leading to a dead cable. 

 

Pass-Through RJ45 Connectors: The front of the connector is completely open. You push the wires all the way through the plug, allowing you to visually verify that the color-code order (usually T568B) is 100% correct before you crimp. A specialized pass-through crimping tool then crimps the pins and slices off the excess wire in one motion. Pass-through connectors are highly recommended for optimal accuracy and speed. 

 

How to Choose the Right RJ45 Connector 

To ensure perfect network stability, follow this simple checklist when purchasing your connectors: 

 

  • Identify your cable type: Check the text printed on the jacket of your Ethernet cable. Is it Cat5e, Cat6, or Cat6a? Buy the exact matching connector. 
  • Check for shielding: Does your cable say "UTP" (unshielded) or "STP/FTP" (shielded)? If it is shielded, you must buy a shielded RJ45 connector with a metal shell. 
  • Check the wire gauge (AWG): Ensure the connector supports your cable's AWG (American Wire Gauge). Standard is 23-26 AWG. 
  • Consider your skill level: If you are new to making custom Ethernet cables, opt for pass-through RJ45 connectors to eliminate guesswork. 

 

ShowMeCables offers a wide selection of RJ45 connectors, including Cat5e, Cat6, Cat6A, shielded RJ45 connectors, pass-through connectors, Ethernet patch cables, bulk Ethernet cable, keystone jacks, patch panels, and structured cabling accessories for enterprise networking, data centers, and industrial installations. Their networking solutions are designed to support reliable Ethernet performance, high-speed connectivity, and scalable structured cabling infrastructure. 

 

Frequently Asked Questions (FAQ) 

 

Can I use a Cat5e connector on a Cat6 cable? 

No, it is highly discouraged. While you might physically force it to fit, Cat6 wires are thicker than Cat5e wires. Forcing them into a flat Cat5e RJ45 connector will strip the internal jackets, cause the pins to misalign, and result in severe speed drops or a completely dead connection. 

 

What does 'RJ' stand for in 'RJ45'? 

RJ stands for "Registered Jack". It is a standardised telecommunication network interface for connecting voice and data equipment. The "45" represents the specific standard designation for the 8-pin, 8-contact (8P8C) plug used for Ethernet networking. 

 

Do shielded RJ45 connectors improve internet speed? 
No, shielded RJ45 connectors do not directly increase internet speed. Their primary purpose is to protect Ethernet signals from electromagnetic interference (EMI) and radio frequency interference (RFI). In high-interference environments, shielded connectors help maintain stable network performance and reduce packet loss. 

 

Can I use the same RJ45 connector for Cat5e, Cat6, and Cat6a cables? 
No, RJ45 connectors are designed to match specific Ethernet cable categories. Cat6 and Cat6a cables use thicker conductors and different internal spacing than Cat5e cables. Using the wrong connector can lead to poor crimps, reduced speeds, signal interference, or complete connection failure.