There’s NO WAY this works

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Ethernet splitters are all over the internet, but aren’t they just a scam to steal from the uninformed? Well, mostly. But with a little knowledge of the history of networking, you really CAN run two devices over a single network cable!

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CHAPTERS
—————————————————
0:00 Intro
1:15 Andy's Car Collection
1:14 Let's try them out!
2:16 The Headphone Splitter
4:06 What's going on here?
5:40 Networking like it's 1999
6:51 But Linus…
8:55 Outro

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60 Comments

Linus Tech Tips

Since reading comments from you beautiful people, we want clarify a couple things. First, the fact that ethernet is digital (as opposed to analog) is not the reason that these splitters don’t work. In fact, some digital signals can be split, such as I2C, DTV, or ARINC.

Second, many other commenters are suggesting using these splitters as passive hubs, but while in the past that could have been a possibility, these splitters aren’t wired correctly for that . The transmission pins on the sending device need to connect to the receiving pins on the other end. Simply wiring pin 1 to pin 1, 2 to 2, etc. as we see here does not work.

While some of those old/deprecated features of the earlier ethernet standards could have enabled devices similar to these to work with very old network adapters, few, if any modern network adapters support these features and, ultimately, the wiring diagrams presented on the product page for these don’t suggest that the seller intends customers to use them in that way.

Our apologies for not making all this obvious in the video! Now here’s some link to real solutions:

Buy a TP-Link 5 Port Gigabit Ethernet Switch: https://lmg.gg/lp5ev
Buy a TP-Link 5 Port Ethernet Switch: https://lmg.gg/3F5f5

Purchases made through some store links may provide some compensation to Linus Media Group.

    Lestify

    Hi i love your content. Your the best

    mananc portofele

    ❤❤

    tech guy with bloons

    when the h

    Aners

    Split me

    TripGamingWolf

    the earliest ive been

JS 2K

Time to daisy chain splitters into a Christmas tree of sadness.

    Lestify

    Ok

    Weepsy

    😔

    Hubert Fernandez

    How many times do you think that’s been said😂

    Nicholas John DeAugustine

    🎄😢

    informitas 0

    Aren’t they all?

Nikola Manolov

This is actually build pretty robustly. Shame that all the engineering time went into the case design and non went into electrical design.

    cyberpass

    Well…They actually do work! Linus is wrong with this video. Collision detection is built into the Ethernet spec. There was a time when you’d buy Hubs instead of Switches.

    Nikola Manolov

    @cyberpass Really? This can work? In that case I have a dumb question – why didn’t it on the laptops in the video?

    Tsuppi desu!

    @cyberpass did you skipped the video or what.. he did said it work.. but with a huge asterisk of “one at a time not at the same time”

    Stephen P. Thurman

    @Nikola Manolov For this particular one to work, the best option would be one of the devices being on a crossover cable or cables that are already set up for only 4 wire which they do make. I have one sitting on my desk right now that came with my Phillips Hub. They do make legit splitters that do the same as what Linus showed with their homemade one using 4 wires per connection. The problem is with the very poor QA in many places that can’t turn around and rip these bad ones apart and fix them, so they sell them off cheap to unsuspecting techno-noobs.

Joshua Tatro

It’s honestly impressive these companies realized less technically inclined people would search for “ethernet splitter” instead of an actual switch, then made a product that looked exactly like what said people were expecting, albeit somehow worse and more expensive than a 2-port ethernet switch. If only they had used their powers for good…

    internet explorer

    it should’ve worked like a hub if they configured it correctly i guess??

    Secret_Takodachi

    “And so one more finger curled up on the monkey’s paw”…… 😂❤

    veto_5

    @internet explorer that’s exactly what a switch does

    edit:
    ok nevermind I’m wrong, still if you want to explain me the difference go ahead, i like reading explanations 🙂

    henry55430

    When money is involved, rarely are the motivations humanitarian.

    Mark Barbarich

    @internet explorer I guess I’m a noob but I always kinda assumed these things are basically a hub? what is the diff?

todayiroam

The “DIY” version is also available commercially and has been for years. In times when 100mbit was still pretty much standard I have been using them for Mir than one customer. If you image search for “Delock Rj45 LAN Anschlussverdoppler” you can find a model that shows the wiring on the casing.

Sven Hoffmann

Hey Linus, nice video. Thou I want to clarify that there are in fact many real spliitters on Amazon that are wired just as you hacked your splitter. I work as a electrican in Germany and can tell you that I see those splitters quite often used. Especially if you have one outlet and want to connect a landline phone as well as a printer for example. If you have a bigger infrastructure and don’t want any devices which would need extra power, could lower your network security or are a point of failure and you don’t need the transfer speed (e.g. phone and printer) it’s for sure a valid option (e.g. kwmobile, they even printed the wiring diagram on the connectors)

    Fity Bux

    Thank you! Not everything plugging into an RJ45 jack is using the Ethernet protocol. RJ11 can plug into RJ45. (As can many hobbyist projects.)

Jackbob

When I was about 12 or so, and didn’t understand these concepts, I searched for ethernet splitters in order to use my Xbox and PC on the same cable.
Luckily I got one that was setup in the same way as the one you made!
And this was way before anyone worried about any 100mbit connections, so I would never even have noticed the drop in speed. Worked great for my usage!

    Astron8

    I know I wouldn’t notice. Speeds here in Jamaica are on average 70mb/s, it’s a good day if we reach 148. So I definitely won’t notice anything wrong with my speeds.

John_Hmstr

This is one of those things everyone who did networking and phone systems in the 90’s and early 2000’s knew of and did. The catch was when you encountered someone who had split out the pairs (or worst of all randomly selected wires) in a custom way and you had to test or trace them out. 🙁

lesson learned from this pain. Leave notes understandable by the next guy on the inside of the panel or on a label.

    Beardy McBeardface

    Tell me about it! When these were incorrectly wired, split the pairs and then connected to long runs, the error rates reported by the switch were through the roof!

    But of course the guy who made it insisted that it was correct, because he tested it with one of those super cheap DC based continuity testers, which cannot find split pair problems because it just tests for continuity and not SNR with balanced AC signals etc. LOL

    The Baker

    … cause the next guy’s gonna be you. 🙂

Cristian Balas

Those devices are actually a gold mine for DIY electronics projects (non-ethernet). I recently used a lot of them to split multiple signal wires very cheaply. Ethernet cables are so cheap and they provide 8 wires inside that can be used for anything.. and those devices provide a very nice solution to duplicating the signal

    grant s

    yes, yes, yes. I’m using a few for cat5e carrying balanced audio to several studio monitors.

    henri rapp

    @grant syup, I’ve used them for studio headphone systems from Furmann.

    Flow Wizardz

    Like the connections in treadmills

    Jack Kraken

    I heard they use them to send HDMI signals even further, you can even get HDMI to Ethernet adapters for this very reason!

    Lennard Faber

    I’ve used them for adding terminators to a cat5 cabled CAN-bus system.

Tom Birkland

I appreciate the updated comment from LTT about why these splitters weren’t wired correctly as hubs. I remember using an ethernet hub about 25 years ago on my home network and it worked, but not well, particularly when speeds increased. I am not technically savvy enough to really know the difference between a hub and a switch (I just now read up on this difference), but I do know that, 25 years ago, it wasn’t possible to buy a decent switch for ten bucks. Times have changed.

    Lord R

    A hub, simply put, is basically a dumb switch. It has a single I/O that communicates with the rest of the network, and all other ports connect to endpoints. Regardless of a message’s destination the signal propagated to every single port on the hub.

    This is in contrast to a switch/bridge, in which a signal is only propagated to the correct endpoint using a physical address.

anekroth

Hi Linus, random network engineer speaking. That splitter might work if you change all of your network interfaces to half duplex. Half duplex would need to be set on both of the computers connected to the splitter as well as the switch port the splitter plugs into. Half duplex uses a protocol called Cable Sense Multiple Access with Collision Detection (or CSMA/CD for short). Its a protocol that harkens back to the days of yore when network devices communicated over a single wire (like token rings and hubs). On a Windows PC you should be able to change the duplex settings from the network device properties in device manager. As for the switch, you will need a managed switch that allows you to change the port settings.

    Ashvin Lakshmikantha

    Thank God there are other network engineers here!!

    Zach

    You mean Carrier Sense

    Trevor Butler

    yeah I was thinking the same thing. Effectively those splitters are just a shitty hub. CSMA-CD is enabled in half duplex settings, but not sure if the consumer grade switch supports half duplex.

    David Schwartz

    Yeah, thanks. I was on the verge of screaming at my computer screen: “google how Ethernet hubs worked bro”.

    With that said, I wonder how tested most NICs are these days to work in a collision domain containing more than two devices. That’s all modern NICs usually have to deal with thanks to the advent of the switch.

    Remo

    I experimented exactly that in one of my projects, and it doesn’t actually work. Reason being standards like 10BASE-T, even when set in half duplex mode, still uses the same two pairs as tx/rx as full duplex, but there is no way to electrically connect those two pairs together so all devices on the bus can share them. I did find there’s a 10BASE-T1S standard that does exactly what I needed but the ethernet chip I had didn’t support it so I didn’t continue that.

    edit: by “work” I meant all devices connected together this way can talk to each other. I was able to get one device to talk to other two even at full duplex, but not between all three devices I had at the time.

    edit2: I was actually experimenting with 10BASE-T, not 100.

Dr WhoStrange

The splitter you constructed is how the legitimate splitters are wired. They would often have a cabling diagram displayed on the top of the splitter. It was useful when things like switches were more expensive or you needed that one extra port in a location without needing a powered device. It’s like the Amazon stores have thought ‘oh yes, we can replicate that product’ without understanding what it’s actually doing.

    Andy Mapp

    Exactly this. I still find these in Businesses to this day! Either 2 sets of 1,2,3,6 for 2 data connections, or 1 x 1,2,3,6 and 1 x 2,5 (for telephony). With vlanning and gigabit passthrough on newer IP phones, they’re a lot less common now.

    Never buy from somewhere that doesn’t display the wiring diagram, but as Linus eludes to, if you’re looking at one of these, there is probably a better solution…

    nberedim

    ​@Andy Mapp I use a pair in my house. Pass Phone/Data from my CPE to the main living room

Do RC

It’s interesting to see this. We actually had a few of these at a doctor’s office I worked at years ago. They added patient portals to each office and there was only one Jack available. Rather than put switches in we just did exactly what you did there and split out the connection. Worked fine

Ripskin16

This was a fun trip to the year 2000. Had a job in a home theater company in high school doing some networking and such with them. Someone paid an electrician to run their network. Bad idea as they only ran one cable vs two for two sides of the wall. Hubs were very common back then as switches were just coming in and fairly pricey vs this video so we did just that, split the pairs and made two jacks one for each room at half the speed of the rated cable total. Worked fine, happy customer who understood what we did and its limitations but very funny to see this.

Michael

For nostalgia and a complete picture:
in Europe similiar splitters were common to split a 4x2pair wire into 100Base Ethernet on pins 1236 and ISDN S0-bus on pins 3456. As ISDN was a bus you also could actually run up tp four devices (i.e. telephones) simultaniously on such “split rivers”, but only middle pins 3456 were ever used.

Dyingwolf

Working at Radioshack I heard this a thousand times. We had an adapter that was exactly like the adapter featured in the video. They would refuse to buy the slightly more expensive ethernet switch regardless of how much I protested. Some of them came back and usually apologized; others I’m sure went to other stores to avoid seeing my face again lmao

    Dominique Beaulieu

    Was it the white triangle shape with 3 ethernet port? If yes i had it and was working not so bad.

    Dyingwolf

    @Dominique Beaulieu nah it was two ports and two came in a pack

Avenga76

You used to be able to buy splitters wired exactly like the one that you made. I used them a lot in the early 2000’s when network switches and hubs were too expensive, and most house wiring only had one cable to each room. Back then everything was 100BaseTX anyway so you weren’t losing anything. The brand I used to use had the wiring diagram on a label on the side of the splitter so you could make sure you had the right ones.

Bizzmark

It was actually kind of shocking to me, earlier in my career (10-20 years ago) how common splitting a CAT5 (or even older) cable in half is in retail environments. Tons of connections at front of house cash registers with the POS on 4-conductor data, often with the other 4 being used for POTS phones. They’re still out there being used.

    Richard Johnston

    I was thinking the same thing. Used them in supermarkets when I cut my teeth in IT back in the early 2000’s. In fact, I still have some of those exact same 20 year old splitters in use in my house today!

    Beardy McBeardface

    I know of a national stock exchange which also used them. There’s nothing wrong with their use, if they’re use correctly.

    We often mixed connections, including 2 wire NEC Dterm phones with the use of these splitters and appropriate wiring on our Krone frames.

garmack12

There are actually old proper Ethernet hubs from when switches were more expensive. They were used a lot in industrial applications because they were relatively low bandwidth. They did however use electronic repeaters instead of just tying terminals together. The downside is that without switching there was a lot of packets being destroyed by two devices transmitting at the same time.

Off The Clock

Hey Linus – if you was thinking about splitting a fibre cable you could always look into a WDM (wavelength division multiplexing) which uses different wavelengths along the same medium to split the transmission – it may require actual fibre splicing but I know this is used for residential properties on fibre networks (in some countries)

It may be overkill for a home network but could be cool to explore? Just a thought!

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