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I have a Verizon router that only has 3 LAN ports. I want to use a splitter in one of the ports so I can have an additional port. What do I use?

DavidF
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    the best way to think about it is that an "Ethernet splitter" is a device called an "Ethernet Switch" (or a hub though that is really old technology). – Frank Thomas Oct 03 '22 at 16:59

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You can't split Ethernet like a water pipe or a TV aerial, it is a point to point communication.

What you can do is change the number of points available to you.

An Ethernet Switch [or older-style Hub] can take one of the sockets from your router & then split it out to 4, 8 or more new connections - each retaining its point to point nature.
You can get these for as little as $£€ 10 - 15 on Amazon/eBay etc.

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In its simplest form, this just gives you 'more sockets'. The device itself is invisible on your network, it simply passes messages along to their intended destination, just as though your router had more sockets of its own.

As mentioned in comments - avoid these things…

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There are two types, equally as bad. [They do have their uses, but can be a bit of a trap for a beginner looking only for "the cheapest, easiest way to do something".]
One type allows two connections at full speed, but only allows one device at a time to use it, it will not 'share'.
The other must be used in pairs and will potentially drop your ethernet speed by a factor of 10, from 1000Base-T to only 100Base-T. They work by sending two distinct sets of 4 wires rather than one set of 8, which is what is needed for full Gigabit Ethernet.
As you have to buy them in pairs to get them to work at all, by the time you've done that you could have bought a proper Switch.

Tetsujin
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    For more detail, see [Why do they sell Cat 5 Ethernet splitters if you can’t split the signal?](https://superuser.com/a/1465201/245275) – Chris H Oct 03 '22 at 11:56
  • @ChrisH - good call - those things are designed to catch out the unwary. – Tetsujin Oct 03 '22 at 11:57
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    in 2022, I doubt you'd find a hub which wasn't new old stock or old old stock – Journeyman Geek Oct 03 '22 at 12:25
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    @Tetsujin They do have legitimate uses in some office/industrial settings. If you truly don’t need gigabit Ethernet, and you can’t pull new cables to create additional drops (this is unfortunately more common than it sounds like it should be), they’re a perfectly reasonable way to add another connection somewhere where you need one. – Austin Hemmelgarn Oct 03 '22 at 21:16
  • I'm sure *somebody* has made a PoE-powered switch shaped like your second picture. – Mark Oct 04 '22 at 03:49
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    @AustinHemmelgarn - sure they do. I agree, but you need to know why & what for. In circumstances like this, at beginner level, they're just a bear trap waiting to catch out the uninitiated. – Tetsujin Oct 04 '22 at 07:22
  • In regard to the "hub" word - the first improved hub was initially a "switching hub" and then was shortened to simply "switch". The "hub" word illustrates the topology and not the internal workings, so it is almost correct to say "hub" in 2022. – fraxinus Oct 04 '22 at 08:36
  • @Mark I'm a fan of wierd hardware and I've never come across a '3' port poe switch before - most switches have a certain depth – Journeyman Geek Oct 04 '22 at 09:28
  • @JourneymanGeek I have seen PoE injectors with 3 RJ45 ports like that. Ethernet in, PoE out en the 3rd one was used to supply power from a wall-wart PSU using another UTP cable. Stupid design... People kept wiring them incorrectly. Manufacturer changed the design on the next batch and replaced the power-only RJ45 with a barrel-plug. And gave the PoE port a fluorescent yellow marking. The fluorescence was actually a nice touch. Made it much easier to see in a dark patch-cabinet. Wish more switch makers did that with the port-labels. – Tonny Oct 04 '22 at 11:05