Using the Plugable USB-E100 Ethernet Adapter
Plugable USB-E100

The fiber optic installer has left the house and you are ready to experience the blazing gigabit speeds you are now paying for. So you fire up your computer, connect to the internet, and… it’s as slow as ever! What went wrong?

It could be a lot of things. The connection between your computer and the worldwide internet is like a pipe. A huge pipe may be connected to your house, but if the interior pipes are small or clogged, or if the faucet is almost closed, not much water is going to flow. If a huge leak is diverting water to the basement floor, not much is going to get to the faucet.

The secret is to ensure that every element between the your home’s internet connection and your computer’s screen is capable of handling your maximum speed. So let’s take a look at the things that can throttle that speed and what you can do about them. We’ll start from the outside and work our way in.

A dripping faucet

Your Connection: How Big is the Pipe?

When you signed up for the internet, your internet service provider (ISP) made you some promises. Along with providing access to the wide world of cyberspace, they probably promised a certain amount of information in a certain amount of time. Just as the size of the water pipe to your house determines how much water can flow into your home, the capacity of the internet pipe into your house, called “bandwidth,” determines how much data can flow.

Water delivery is typically measured in gallons or liters per minute. Data from the internet ultimately consists of units of information called bits. Bandwidth is measured in bits per second.

A single bit is a very small piece of information. It takes 8 bits (called a byte, usually represented by a capital “B” in abbreviations) to represent one single letter or number on your computer screen. A medium-resolution photo might be one megabyte (one million bytes or 1 MB), which in turn is 8 million bits (or slightly more, since some people use 1 kilobit = 1024 bits). So if your ISP promised you 8 megabits per second (8 Mbps) it would take a little over a second to deliver that photo once the download started.

In the home, bandwidth can range anywhere from 28.8 kilobits per second through the modem on an ancient AOL account to 1 gigabit (1 billion bits per second) if you are one of the lucky people to have a direct fiber optic connection to your home. Business accounts with fiber optics can range much higher. Of course these are theoretical limits. Reality can be harsher.

Ultimately, the bandwidth provided by your ISP will be the upper limit of what you can expect. Keep in mind that ISPs typically promise speeds “up to” their offer. This means you might be able to obtain the promised speed under perfectly ideal conditions. In the real world with outages, slowdowns, and that annoying neighbor running an unauthorized game server on the same cable as you, speeds will likely be less.

Furthermore, if you do any kind of speed testing (more about that later), you can expect to see a figure lower than the raw bandwidth. This is because not all bandwidth is used for data. Each chunk of data (called a “packet”) sent over the network is surrounded by information about the type of packet, where it is going, where it is coming from, and the like. Also, control messages frequently go back and forth between computers to monitor the flow of information. This means that around 10 percent of your bandwidth is “overhead,” which may not be counted in your test.

These days, most broadband is either DSL, which uses telephone lines, or cable, which uses the same cable as your television. Internet providers using these two methods typically offer download speeds between 5 and 100 Mbps, with DSL being on the slower end. The amount varies according to the type of internet (DSL or cable), the service level you pay for, and with DSL, your distance from the nearest telephone exchange.

However, as mentioned above, this bandwidth is only potential. It does not become reality until you use it at your computer. In the next sections, we will examine the chain of components from gateway to computer that determine how close actual results approach that promise.

A router with WiFi and LAN capabilities

Modem and Router: How Wide Is the Gate?

These days, almost everyone has a router on their network. Sometimes it is a combined modem and router supplied by your ISP.

A router is a very good thing. Not only does it allow you to create an internal network for several computers, but it also provides a barrier to the Wild West of the external internet, making it harder for bad guys to get in.

A router acts as a single portal to the internet. It receives all incoming information and sends each packet of data off to the computer it is addressed to.

Because it is the gateway, a router can seriously affect your speeds. First, routers typically support either 100 Mbps or 1000 Mbps. For most home networks 100 Mbps works fine for a cable or DSL connection. But if you are lucky enough to have a fiber optic connection, you’ll need to upgrade to a Gigabit router that supports 1000 Mbps.

Also, if your router wasn’t designed for the number of computers you are connecting to it, things will slow down.

Finally, a router may have problems that slow it down.

Most modern routers come with integrated WiFi support. We’ll discuss WiFi in greater detail later on, but if you are using WiFi and your router’s maximum WiFi speed is less than that of your computer, the router will be the bottleneck. If you have fiber optic internet, you’ll probably want to avoid WiFi whenever possible, since only the newest WiFi type, 802.11ac, can support Gigabit speeds, and even that requires ideal conditions.

If you are supplying your own cable modem on a cable network, you’ll want to be sure it is capable of the speeds promised by your ISP. Cable modems follow a specification called DOCSIS, which is available in versions 1.x, 2.x, and 3.x. Each version offers increased performance, but these days ISPs offering high speeds are specifying DOCSIS 3.0 or higher, which supports speeds up to 150 Mbps.

Ethernet cables
Ethernet Cables


If the router is the heart of your network, the Ethernet cables are the blood vessels. And just like vessels in the body, if something clogs them up, trouble will follow.

A good way to check the cable to your computer is to plug the computer directly into your router or modem with a known good cable of the correct type (see below) and see if your speeds improve.

The biggest threat to successful passage of information through the cable is interference. The signal in each wire in the cable creates a magnetic field. When two wires run next to each other, this magnetic field in each induces a current in the adjacent wire. This current becomes electronic noise that overlays and degrades that wire’s original signal. The longer they run together, the greater this effect. In an Ethernet cable, where you have eight thin wires inside running next to each other, this can really cause problems.

Interference is minimized twisting together pairs of the eight signal wires in the cable. This ensures that two wires with different signals won’t sit next to each other long enough to cause problems. Each pair of cables has a different number of twists per inch to further isolate each set from the others.

Ethernet cables are sold in different categories that express how protected they are from interference and therefore how fast they can carry data safely. When data speed is increased the cable becomes much more sensitive to interference and more protection is needed. Naturally, higher category cables that offer more protection are more expensive.

Three categories are useful in most situations: CAT 5, rated at 100 Mbps; CAT 5e rated at 1000 Mbps; and CAT 6 rated at 10,000 Mpbs. CAT 5 is fine for most internet access through DSL or cable, while CAT 5e works well on connections over 100Mbps, as well as Gigabit business networks and home fiber optic connections. CAT 6 is probably overkill for most home networks, but is useful for business networks over 1 Gbps (Gigabit per second).

Even if you have the right cable, inference can enter in other ways. Many Ethernet cables are not shielded, which means they will pick up interference from any wire nearby with a strong AC current, such as power cables, extension cords, and electrical wiring in the walls. To avoid this, don’t run Ethernet cables alongside power cables and extension cords. Never bundle them together with these wires, no matter how neat it looks.

Finally, it may seem like a good idea to buy that huge roll of Ethernet cable at the home improvement store, make your own cables, and wire your whole house. But you may want to leave it to a pro or buy pre-made cables of the appropriate length. Cable terminations on higher-rated cables are very sensitive to interference if not done correctly, and if you are pulling cable through walls, you might easily run alongside a AC supply line hidden inside.

Even the best cables can wear out over time, especially if they are frequently plugged and unplugged or used in a place where they may be stepped on, run over by the wheels on a chair, or flexed a lot. A loose connection or broken wire may connect and disconnect intermittently, causing lost data and degraded performance. Whenever there is a speed or connection issue, it’s a good idea to try a different cable as an early step in troubleshooting.

Some people use powerline Ethernet systems where the signal is sent through their home’s AC power system. While these can allow you to avoid long runs of Ethernet cable, we have seen cases where a low-quality signal caused poor performance and even cases where excessive voltage burned out one adapter after another. Your mileage may vary.

Switches and Hubs

Switches and hubs allow you to connect a single Ethernet cable to several computers. Like routers, they are rated for different internet speeds. If you are hoping to connect at more than 100 Mbps, be sure to get components rated for Gigabit networks (1000 Mbps). A switch or hub could also be faulty, causing problems. A way to check this is to temporally remove the switch or hub and connect the computer directly to your router or modem. If speeds improve, the switch or hub was the problem.

A multi-user setup using many Plugable UD-160-M Thin Clients

Other Computers on the Network

Naturally, if your computer is sharing your network with other computers, tablets, or phones, it is also sharing network resources with them. If speeds are disappointingly low, try disconnecting all other devices from your network.

Turn them off or unplug their network cables. Turn off WiFi on any wireless devices. Try the test again, and if speeds increase then one or more of those devices was slowing things down. Isolate the problem by reconnecting devices one-by-one until you see the speed go down again. The one you just connected is the likely culprit. If no one was using that device, it might have been downloading data in the background, or it is possible that malware on it is accessing the internet.

Your Computer

You’ve optimized your network from the router to your computer and it’s delivering data at maximum speed. But it still takes forever to load that webpage, and your PC game character keeps dying of network-induced lag. It’s likely a problem on the computer you are using.

Plugable's range of USB Ethernet adapters
Plugable USB Ethernet adapters

Network interface

The network interface is where the data hits the computer. It’s the port or WiFi adapter that receives the data from the air or cable and translates it into something the computer can understand. No matter how fast the data arrives at the interface, it will only pass through as fast as the interface can process it. Many things can slow it down.

It’s important to remember that an interface that is capable of higher speeds than your network provides will not help things go faster. Spending money on a Gigabit network card won’t give you 1000 Mbps if your ISP is only supplying 25 Mbps.

Furthermore, a high-powered interface won’t help you if another device or computer on the network is hogging up bandwidth, or if malware or CPU intensive software is slowing things down on your computer.

Plugable sells two types of network interfaces: several USB to Ethernet adapters and a WiFi adapter. We’ll discuss WiFi later on. For information on finding the right USB Ethernet adapter for your network, see our blog post on selecting the right USB-Ethernet adapter for your network. It mainly boils down to making sure the adapter is compatible with your computer or device and that it can handle your maximum speed.

But what if you have the correct adapter and you’re are still not seeing the speeds you hoped for? For example, let’s say your ISP promises 200 Mbs and you are only getting 25 Mbps. You buy a Gigabit USB-Ethernet adapter like Plugable’s USB3-E1000. But when you try it out, there’s no improvement. Is the adapter bad? Generally not. When adapters are faulty, they usually fail completely or have intermittent connection issues, not speed problems. So it is probably be something else.

Possible speed-reducing problems on your computer

  • Conflict with your computer’s WiFi adapter: When testing internet speeds, always turn off every other adapter besides the one you are using. Otherwise, your computer may use the slower adapter to send some or all of the data, reducing test results.
  • Smart-Byte software on Dell Inspiron laptops: Dell has installed software called Smart-Byte on many Inspiron computers that can cause network slowdowns. Read this blog post if this may apply to you.
  • Other programs using the network: If you are testing your adapter, you don’t want any programs using the network other than the browser window or testing program you are using. For example, if another program is downloading something during the test, that data will not be seen by the testing server and skew the results. If BitTorrent or other torrent program is running, this can affect speeds. Close all other programs and browser tabs during the test.
  • Malware: Rogue programs like viruses, trojans, spyware, and adware can take control of your computer’s network without your knowledge and use it for nefarious purposes. Unexpectedly low internet speeds are one of the common signs of malware, along with unexpected popups, changes to your browser home page without your knowledge, unwanted toolbars, unusually slow operation, and the like. If you have an antivirus, make sure your subscription is up-to-date. If not, install one. Many excellent basic anti-virus programs are free to home users.
    If you suspect malware, run a comprehensive malware scanner like Malwarebytes Anti-malware (the free version works well) even if you have an antivirus installed.
  • Correct Port: If you are using a USB 3.0 network adapter, make sure it is plugged into a USB 3.0 port. USB-Ethernet adapters plugged into USB 2.0 ports typically max out at about 250-300 Mbps, well below the 900 Mbps or higher speeds that are possible with a USB 3.0 Gigabit adapter attached to a USB 3.0 port.
  • Elderly CPU: Often older computers have weaker processors and limited memory that can’t handle the highest internet speeds. Also, older computers tend to accumulate more “cruft” such as programs that run constantly in the background and slow things down.
Plugable Nano WiFi Adapter
Plugable Nano WiFi Adapter


Under ideal conditions, Plugable’s USB-WIFINT WiFi adapter is capable of speeds up to 150 Mbps. However, WiFi conditions are rarely ideal, and real-world speeds reflect this. WiFi shares a narrow frequency band with not only every other WiFi adapter in your neighborhood, but also Bluetooth, cordless phones, baby monitors, security cameras–even your microwave. This means WiFi is trying to get your data to the access point through a lot of noise—like trying to talk your friend across the room in a crowded party. When the message gets garbled, the connection slows down, and missed data packets must be resent several times before they are received.

Things to check in the section above also apply to your WiFi adapter. But there are some other considerations for wireless connections:

  • Move closer: If you are getting a marginal signal with just a a bar or two, try moving closer. Walls or floors between you and the WiFi access point will also quickly degrade the signal and slow things down. Keep in mind that the tiny size of the Plugable adapter also means it has a smaller antenna than your cellphone or laptop, and may need to be closer to get good results.
  • Bring the signal closer:. For a more permanent solution for cases where moving closer to the access point isn’t an option, you might consider buying a WiFi range extender that will bring the signal closer to the computer. You can also buy an access point that you can connect to your router with an Ethernet cable and place in a more convenient location.
  • Reposition the adapter: Sometimes interference from your computer’s internal circuitry can cause problems. Try other ports on your computer. A port on the front of the computer is usually better. If possible, avoid using a USB 3.0 port for your WiFi adapter, because a poorly shielded port can produce radio interference and drown out your adapter. It often helps to use a short USB extension cable to move the adapter up and away from the computer. You can also use a long active extension cable like a Plugable 32-foot (10-meter) USB extension cable to move the adapter closer to the access point or router.
  • Eliminate interference: Try temporarily turning off things like security cameras, baby monitors, and cordless phones to see if reception improves.
  • Limit users: Your access point or wireless router is also limited in speed, and each wireless user will consume part of that. If someone else in the house is downloading something while you are watching a movie this will cause problems. Access points in public places frequently slow to a crawl with many users. Be sure you have the highest possible security set on your home’s access point with a good password so that your aren’t hosting a public access point unintentionally and giving away bandwidth (and maybe your personal information).

Testing Your Speed

Most people test speeds using a remote speed testing service like Ookla, DSLReports, Comparitech (raises money for charity), or one provided by their ISP: AT&T, Comcast, Time-Warner, or Verizon. But there are a few things to be aware of when doing this:

  • You are testing more than your adapter or network. Using an external test server tests not only your home setup, including your adapter, but everything between you and the server doing the test. So if your ISP is having a problem, the internet is congested, or the server is on the other side of the country, your results may reflect that.
  • Select a good time. Times when many people are likely to be viewing a movie, downloading files, or playing games, such as evenings and weekneds, often produce inconsistent results. If you aren’t happy about your speed, try again in the early morning to get a better picture of your peak capacity.

I hope this guide has been useful in discovering and eliminating speedbumps on your internet highway. If you have a Plugable adapter, and these ideas didn’t help, please contact us at We are happy to help!

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