Test your internet by cable before you blame the provider

Your internet feels slow, or you are sure you are not getting the speed you pay for, and you are about to phone the provider or pay for a faster plan. Many people say the cause is often in the home rather than at the provider, and some people say a mix-up between two units makes a normal speed look like a rip-off. Both can be checked for free in about fifteen minutes. If you live where one provider serves your address and the line itself is slow, the checks still help you prove it, but the fix may not be in your hands; the last section is for you.

Before you call the provider or pay for a faster plan, test the speed with a cable plugged into the router, and multiply any speed shown in megabytes per second by eight before you compare it with your plan.

One speed, two spellings

Providers sell speed in megabits per second, written Mbps. Download windows and file managers often show megabytes per second, written MB/s. A byte is eight bits, so a speed in MB/s has to be multiplied by eight before it can be compared with the plan. Turned round, a 25 Mbps plan can show at most a little over 3 MB/s in a download window, because 25 divided by 8 is about 3.1.

Some people say this mix-up sits behind complaints about throttling that turn out to be a normal speed. One person reported 2 to 2.5 MB/s on a 25 Mbps plan and suspected throttling; the answer was that 2.5 MB/s is about 20 Mbps, close to what that plan can give. Some people also note that the capital and small letters carry the meaning, a small b for bits and a capital B for bytes, and that they are easy to misread. One person adds that a little speed is always lost to overhead, so a result slightly under the plan is expected.

Test with a cable

Many people say the home network is what limits the speed: the Wi-Fi, the router, a cable or a connection. A wired test separates your home from the provider. Plug a computer into the router with a network cable, close everything else that uses the internet, and run a test. If the result matches your plan, the line and the plan are doing their job, and the slowness is in the house. If it falls well short, go to the section on the provider below.

If the cable result is fine and Wi-Fi is slow, some people say wired is the steadier choice for things that matter, and that when you must use Wi-Fi a newer standard and less interference help. Other suggestions each come from one person. Changing the Wi-Fi channel can help against interference. Moving to the 5 GHz band avoids the crowded older band, though another person warns that 5 GHz passes through walls less well. A poor router is a likelier cause than the plan’s top speed, and a better one can bring wireless close to cable. An older router or computer can have network ports limited to 100 megabits, which holds back a faster plan whatever the cable. On a cable modem, a loose coaxial connector can cause poor signal, and tightening it can fix that. One person also says there is no reason to pay extra for a higher-category cable for ordinary home use.

Not everyone thinks Wi-Fi is the weak link. One person says that on an ordinary plan the plan itself is the limit, and Wi-Fi is quick enough that you cannot tell the difference. Whether Wi-Fi is the limit depends on your plan: a plan slower than your Wi-Fi cannot be held back by it. You only need the cable for the test: some people note that running a cable through a house is a chore, and that is a fair reason to stay on Wi-Fi.

Close what is quietly using it

Some people say cloud backups, updates and browsers can use up the line, and that your computer’s activity or task monitor shows which program is doing it. Check that before you test. Some people also say that for online games, delay matters more than top speed, and that the two are separate things; they suggest a router setting that puts that kind of traffic ahead of big downloads. This page does not walk through router settings. The router’s own manual does.

Run the test so the number means something

Many people suspect that speed tests run by providers, or tied to them, can look better than daily use, and some say providers favour the well-known test sites, so results look better than daily use. Others, including one person who says they work on cable lines, say that many slow complaints turn out to be on the customer’s side: the router, a VPN, old equipment. Others again say the test site matters less than how far away its server is and how busy it is. This page cannot settle which is right, so it leans on checks that work whichever is.

Test at different times of day, including the evening. Try a second test site. Some people say a distant server’s result includes the rest of the route, not only your provider’s part, so it says less about your provider. One person says downloading a large file from an ordinary website is a more lifelike test than a test site. Write down every result with the date and time. One person suggests running a test on a schedule and keeping the log, because a log over days shows sustained under-performance better than one bad moment. In the UK, Citizens Advice also tells you to use Ofcom’s speed checker and note the results.

If the numbers point at the provider

If the cable test is well under your plan at different times of day, a call is reasonable. Some people say a call can get a line fault fixed, such as noise on the line, and some say throttling stopped after one. One person says a call about a small gap gets nowhere and may end with the plan being cut to match the price. One person says calm, detailed, factual explanations are taken more seriously than anger. One person says the first-line support they reached offered troubleshooting such as moving the router instead of admitting a fault, and another that a representative blamed their computer’s hardware. Have your dated results in front of you. One person says you do not need to prove poor performance in order to switch to another provider.

Check what your plan promises. Some people say plans are sold as “up to” a speed, which is not a promise of that speed, and that rural or fringe service is sold as “best effort” and can be far below the advertised rate. One person says some providers leave customers on old or discontinued plans without telling them, so check which plan your bill says you are on.

In the United States, the FCC says providers must have a label for each home and mobile broadband plan, and that you should look for it at any point of sale, online or in a shop. It must disclose the price, introductory rates, data allowance and speeds. If a provider is not showing labels or has posted wrong information about its fees or plans, you can file a complaint through the FCC’s consumer complaint centre. The FCC said in July 2026 that it is changing the label rules to make them easier to read, so look at the label your provider shows now. In the UK, see the answer on leaving a contract in the questions below.

One thing not to do: one person warns against cutting your plan to match the slow speed you are getting. A cheaper plan has a lower top speed, so you may end up slower still. Whether you need the plan you have is a separate question, and the speed guide in the questions below gives rough figures to check it against.

If the cable test is slow too, or you cannot get a good line

Some people say distance from the exchange or DSL equipment, or no fibre at your address, can hold the speed down whatever plan you buy. Some say that where there is no competition providers may deliver speeds far below what is paid for and leave you little recourse.

If you are choosing a place to live, some people say what the provider’s online availability tool says can be wrong, and that you should phone the provider with the exact address. One person reported an online check that said service was available, found it was not once they moved in, and got a credit after a dispute. One person lists asking the neighbours what they use among the checks. One person says a phone call can fail too.

Cost is its own problem. In the United States, the FCC’s Lifeline program takes up to $9.25 a month off a phone or internet bill for people with a household income at or below 135 percent of the federal poverty guidelines, or who are on programs such as SNAP, Medicaid, federal public housing assistance or Supplemental Security Income. It allows one benefit per household, and you can apply at lifelinesupport.org. The earlier federal Affordable Connectivity Program has ended. If you have no home connection at all, there is a page here on borrowing internet from the library. In the UK, councils such as Kent County Council say some providers offer cheaper “social tariff” packages to households claiming Universal Credit or other benefits. Ask your provider whether it has one; Citizens Advice can help if you are not sure.

Who this page is not for

If your internet is satellite or mobile data, the cable test does not apply, and the numbers mean something different. If you want router settings or help running cables through a house, this page does not cover them. And if your cable test is slow, the line is slow wherever you live, and you have one provider, then no test here will change what is available at your address.

Whatever happens next, you now hold a number with a date next to it, and that is what a call to the provider needs.