What you are looking at is not just a simple cable, but a USB-to-serial adapter with electronics built in to handle the conversion. It isn't an ethernet cable, and it doesn't require Category-5E. Cisco has had serial-to-serial rollover cables forever, using telephone-grade cable.

If you have a standard Cisco rollover cable, which comes with just about every Cisco device, all you need is a USB-to-serial adapter, and the software which comes with the adapter. This is just those two things combined.

Answer from Ron Maupin on Stack Exchange
Discussions

RJ-45 to USB Adapter for console connection?
Hello, I would like to configure a Cisco 3600 Router with my laptop, however, I do not have the RJ-45 to DB-15 cable, nor do I have the DB-15 serial port on my laptop. I also do not have the required DB-15 to USB adapter that would be needed to assist me in connecting my computer to the router. More on community.cisco.com
🌐 community.cisco.com
November 26, 2010
How to: USB RS232 to RJ45 interface pinout | Hardware Canucks
Hello everyone. I am not able to find a clear guide of wiring a usb serial to an rj45 jack. It is for a cisco console connection from my pc to a router. There is a serial usb cable in ebay... 6pin FTDI FT232RL USB to Serial Adapter Module USB to TTL RS232 Arduino Cable R3 | eBay But, i want to... More on hardwarecanucks.com
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December 21, 2014
USB to RJ45 Cable for Console?
Does Cisco, or anyone else do a cable that will allow me to connect my USB only laptop to a console port on a Cisco device? ... Just do a google search for 'USB Serial' and you will find a lot of different models. ... Was hoping there might be an All-in-one.....USB to RJ45 cable. More on community.cisco.com
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August 26, 2008
Access the console using RJ45-to-USB adapter
Hello, I was trying to connect to my switch using RJ45-to-USB adapter, like the one shown in the photo: I failed to get access, and I got the following messages under Linux's dmesg : [ 183.932077] usb 1-1.2: new full-speed USB device number 7 using ehci-pci [ 184.012073] usb 1-1.2: device ... More on community.cisco.com
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February 5, 2018
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Waveshare
waveshare.com › wiki › USB-TO-RJ45-Console-Cable
USB-TO-RJ45-Console-Cable - Waveshare Wiki
Connect the USB port of FT232 to the USB port of the Android phone with the OTG adapter cable, and then connect to another FT232 and computer via the USB port.
Top answer
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44

That RJ45 to USB cable is not an Ethernet adapter.

It might superficially look like one, but it’s not.

That cable you purchased is a known as console cable (aka: Cisco cable or rollover cable). It’s meant/designed to connect your PC to a server (or other enterprise level device) via RS232; aka serial connection or link. That is not an Ethernet adapter, and cannot be used as one at all.

Generally, what you are looking for is a USB to Ethernet adapter that looks something like this:

You would plug the USB side into your PC and then connect the Ethernet end to your LAN via an Ethernet cable. These are fairly common to come by and should be pretty affordable. Just make sure to check if the USB A to RJ45 adapter you purchase explicitly states it’s an Ethernet adapter.

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12

The 8P8C connector (commonly known as RJ45, even though this is incorrect) is used for a lot of different things.

While nowadays its most common use is for (some kinds of) Ethernet, it can also be used:

  • For RS-232 or other similar serial ports (instead of the more common DB-25 or DE-9 connectors), especially for console access on Cisco routers and other devices;
  • For analogue telephony (aka POTS);
  • For digital telephony (aka ISDN);
  • For proprietary telephony systems;
  • Sometimes even USB;
  • And many other things.

The adapter you bought is for the first type: to connect to an RS-232 serial port presented as 8P8C (RJ45). It is completely unrelated to Ethernet.

What you need is a USB Ethernet adapter. They come in many different shapes and sizes, and have varying characteristics and performances (100 Mbit/s, Gigabit, 2.5GbE, USB 2, USB 3, USB-A, USB-C...). You need to make sure the description of the product includes "Ethernet", along with the specs you want.

Some docks (especially USB-C docks) also include Ethernet ports, so it may be an alternative if you need other interfaces (more USB, HDMI, etc.).

If your computer has a USB-C port, you're probably better off using an adapter using that kind of port. Given the low prices of such adapters, picking a 2.5GbE adapter is probably a good idea even if you won't use it at its maximum potential if your switch/router doesn't support such speeds.

While there are a few adapters that take the form of a cable (with a male "RJ45" at the other end like the one you bought), most will have a female connector, and you will then need an Ethernet cable to connect that to the corresponding connector on your switch or router. The advantage is that you can easily change the cable if you need shorter or longer distances (or if the cable or plug gets damaged).

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Cisco Community
community.cisco.com › t5 › network-management › rj-45-to-usb-adapter-for-console-connection › td-p › 1523796
Solved: RJ-45 to USB Adapter for console connection? - Cisco Community
November 26, 2010 - ... In the labs here at Cisco, and at the Cisco Networking Academy I work for, we use the light blue Cisco flat console cable (Male RJ-45 connection and a Female DB-9 Serial connection), and then a USB adapter to hook to our computers.
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Amazon
amazon.com › Cable-Matters-Console-Compatible-Rollover › dp › B078PVJ5ZQ
Amazon.com: Cable Matters USB to RJ45 Console Cable (Compatible with Cisco Console Cable, Rollover Cord) with FTDI 6 Feet : Electronics
Snagless male to male cisco console cable provides a convenient solution for configuring equipment with a console port; A snagless RJ45 connector protects the tab from being torn off and stuck in the console port · Simple installation of this USB to console cable with the FTDI drivers and instructions available for download from Cable Matters; Windows 10 and the latest MacOS usually include FTDI drivers as part of the OS when using this FTDI USB cable
Find elsewhere
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Quora
quora.com › How-do-I-make-an-RJ45-to-a-USB-cable
How to make an RJ45 to a USB cable - Quora
Answer (1 of 2): Hi… I really don’t think you can, if you have to ask here…But, not all is lost.. Amazon sells a cable RJ-45 to USB..about 10 bucks…they also deliver.. Walmart has a media converter device, that does pretty much the same thing… a little more than 10 bucks…
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Genuinemodules
uk.genuinemodules.com › how-to-make-usb-to-rj45-console-cable_a1788
How to make usb to rj45 console cable?
March 15, 2025 - Use the crimping tool to secure the connector to the cable. Connect the Wires: Solder the TX, RX, and GND wires from the RJ45 connector to the corresponding pins on the TTL converter. Double-check the connections to ensure they are correct.
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Hardware Canucks
hardwarecanucks.com › home › forums › pc builders & tweakers corner › guides & how-to's
How to: USB RS232 to RJ45 interface pinout | Hardware Canucks
December 21, 2014 - If you DO get that wire, you can cut the end off the RS232 side and put on a RJ45 and have it work by wiring a DB9 pinout to RJ45 I imagine, or any sort of old school pinout cabling to match your RX/TX/RTS/CTS and power lines. ... If this is to use a console port on routers/switches, then you ...
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Amazon
amazon.com › Console-Essential-Accesory-Ubiquity-Switches › dp › B01AFNBC3K
Amazon.com: USB Console Cable USB to RJ45 Cable Essential Accesory of Cisco, NETGEAR, Ubiquity, LINKSYS, TP-Link Routers/Switches for Laptops in Windows, Mac, Linux (Blue) : Electronics
The computer usb port is directly connected to the RJ45 console port of the device, and you can start working quickly and easily · Widely supports the basic accessories of branded routers, switches, firewalls and wireless LAN controllers with console ports, such as Cisco, Ubiquiti, Juniper, Fortigate, Mikrotik, TP-Link, Huawei, HP ProCurve devices, etc. Note: Please make sure your device has RJ45 console port
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Instructables
instructables.com › circuits › computers
Simple RJ45 DB9 Cisco Console Cable : 4 Steps - Instructables
November 5, 2017 - Simple RJ45 DB9 Cisco Console Cable: Hello everyone, I just bought my first cisco router (2610) and, in order to learn about it I decide to start a blog. The idea its to provide a step-by-step from nothing to something that can be useful in a SOHO environment. The blog still in the …
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Genuinemodules
uk.genuinemodules.com › how-to-make-console-cable-rj45-to-usb_a7655
How to make console cable rj45 to usb?
Wires and Pinouts: Understanding the pinouts for both RJ45 and USB connectors is crucial for creating a functional cable. To create a console cable RJ45 to USB, you will need the following tools and materials:
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YUXUN
yuxun.com › how-to-make-console-cable-rj45-to-usb.html
How To Make Console Cable Rj45 To Usb? - YUXUN
March 18, 2025 - Console cables are used to connect a computer to the console port of a network device for configuration and management. Use an RJ45 cable and reverse the pinout to create a rollover cable. Common baud rates include 9600, 19200, and 115200. Ensure it matches the device's setting.
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ServeTheHome
forums.servethehome.com › index.php
DIY Mini-USB Serial Dongle
April 19, 2019 - A place to discuss servers, storage and networking
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Netgate Documentation
docs.netgate.com › pfsense › en › latest › solutions › netgate-8200 › connect-to-rj45-console.html
Connecting to the RJ45 Console Port | Netgate Documentation
Perhaps GUI or SSH access has been locked out, or the password has been lost or forgotten. A separate adapter is required to make a connection between a computer and the firewall using the RJ45 serial port. This can be a direct RJ45-to-USB serial adapter or a standard USB-to-serial adapter ...
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Infosec Institute
community.infosecinstitute.com › home › certification preparation › cisco › ccst & ccna (entry-level & associate)
USB to Serial/Console Cable??? - TechExams Community
May 9, 2013 - Genuine Newbie here so please help me make sense of what exact cable is needed to go from my laptop into my C2950 console port to start familiarizing myself w/Cisco's IOS. The guy @ BestBuy didn't have a clue what I was talking about (same boat as me), and at Frye's all he said is what I needed ...
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AscentOptics
ascentoptics.com › blog › usb-console-cable
Everything You Need to Know About USB to RJ45 Console Cables for Cisco Routers - AscentOptics Blog
September 5, 2024 - Connect RJ45: Plug the RJ45 side of the console cable into the router console port. Install Drivers: where applicable, install them to the USB to serial adapter, so that it will be able to work effectively.