Why is the WiFi signal full but the speed so slow? Don’t just focus on the number of slots. My desktop computer with three slots is ten times faster than a mobile phone with one slot.

My mother discovered this first. She used her iPad in the bedroom to catch up on dramas, and she was stuck and couldn't connect the scenes. I took out my phone and looked at it. There were three WiFi icons, solid. According to my previous understanding, the number of grids is life, full grids equals fast, and few grids equals slowness. Then the blame should be given to the video website. But the desktop computer in the living room with the network cable plugged in was running the same website at the same time, so nothing happened.

Under the same roof, one smooth and one card. That night, I ran around the house with two mobile phones in my hand, measuring speed and counting at six points in the living room, corridor, bedroom, and bathroom. When I came back and checked the backend of the router, I discovered that the grid count was completely different from what I thought. Let’s talk about the conclusion first: The grid number only answers "did you connect", it does not answer "how fast you connected". The real reason for the slow completion of the grid is often hidden in the layers below the grid number.

Find out first: What exactly does the grid number show?

The pillars in the status bar of the mobile phone are converted from signal strength. When the signal sent by the router reaches your mobile phone, the intensity has a number, and the unit is called dBm. It is a negative number, and the closer it is to 0, the stronger it is. The mobile phone system gets this number, cuts it into three and four levels, and draws it into a grid. The problem lies in cutting it with this knife: From -30dBm to -60dBm, most mobile phones display full range, but the network speed under these two strengths can be quite different. ； From -60 to -70, there may be three bars displayed, and the speed is quite different. The grid is to compress the entire slope into three steps. If you stand on the steps, you can't tell that you have actually slid down half of it.

I finished measuring the six points that night and copied the "display number" and "actual intensity" side by side on the paper. The line that matched the most was like this.: Bedroom bedside -71dBm, two bars ； Bedroom door -58dBm, also two levels. Two locations in the same room look the same. According to actual measurements, one runs at 280 Mbit/s and the other runs at 90 Mbit/s. So when it comes to checking the slowness of full grid, the first step is to bypass the grid number and look directly at dBm.: On some Android models, you can see "Signal Strength" in the WiFi details. On iPhone, click the exclamation mark next to the WiFi name and look at the "Signal Strength" column. ； If you really can’t see it, you can download an app to test WiFi. There is only one rule for reading numbers: -Below 50 is considered good, -60 is still good, and below -70 is the boundary of "it looks connected, but is actually holding on".

Let me add a fair word by the way.: dBm is something that tends to make you more anxious the more you look at it. I later measured the numbers in my house and found that -68 is not a disease as long as the actual measured speed meets your needs. Numbers are used to position yourself, not to force yourself to death.

My family’s actual test account: The number of grids and the speed simply don’t match up.

There's no point in just being reasonable, so please release the account I copied that night. The router is the AX3000T in the living room, with gigabit broadband. Each of the six points is measured three times and the middle value is taken.:

The most eye-catching thing in this table is the row at the bedroom door: The strength is -58, which is better than -61 in the middle of the corridor. The speed is only 280, and it is connected to 2.4G. This is the number one culprit of slow grid speed - the grid you see is the total number of grids, but what your router sends out is actually two networks.: 2.4G and 5G. 2.4G has strong wall penetration, good signal, and high grid count, but the speed ceiling is low. ； 5G is fast, but lags behind two walls. When the mobile phone feels that the 5G signal is weak, it will automatically slide back to 2.4G. The number of bars may not be reduced, or even increase, but the speed will be directly reduced to a fraction.

How do I know which network my phone is currently connected to? You can usually see which frequency band each device is hanging on in the router's background device list. ； Or the "link speed" in the mobile phone WiFi details. Those with a few tens of megabytes are basically 2.4G, and those with more than 800 to 1,000 megabytes are 5G. The iPad at the door of my bedroom showed a link speed of 144Mbps and I was caught on the spot. This problem of "the mobile phone will not let go of which frequency band it holds" is related to the router merging the two frequency bands into the same name. I am Writing WiFi roaming does not switch In that article, the entire mechanism was dismantled: The dual-band router selects the frequency band for you based on its own algorithm. If it is selected conservatively, you will be stuck on the slow network for a long time.

The first real murderer: 2.4G supports full grid, locking the speed

Knowing that the phone has slipped back to 2.4G, there are two solutions. Article 1: Treat the root cause: The backend of the router integrates dual-band, giving each of the two frequency bands its own name. For example, the name of your home WiFi is automatically followed by「_"5G" is the 5G network. Devices that require fast connections can be manually connected to 5G, while smart socket cameras and those that are not in a hurry can stay on 2.4G. The night after the switch was completed at my home, the iPad on the bedside of my bedroom went from 90 MB back to 330 MB without moving a single slot. It was still the same two slots, and the Internet speed more than tripled. The number of grids has not changed at all. This is the most intuitive slap in the face that "the number of grids does not equal speed".

The second way is the lazy version: Without changing the name, adjust the 2.4G transmission power down one level (most backends have three levels: high, middle and low). The power is reduced, and the 2.4G coverage shrinks. Mobile phones find it weak deep in the room, and will be pushed back to 5G. This method has few side effects, but its effectiveness depends on its performance. This is how the mobile phone in my bathroom was pushed back, but the one in the bedroom stayed still. In the end, the solution was solved by changing its name. Another reminder: If you have a lot of smart devices at home, it will be painful to separate the dual-band. Devices such as sweeper cameras that only recognize 2.4G are easy to get confused when distributing the network. This is a pitfall for me. Sweeper distribution network exploded five times in a row I wrote a complete response in that article. Please read it before changing it to avoid a collective strike of the whole family's equipment that night.

The second real culprit: Believe it or not, the space is full and we can’t stand it together.

If the dBm is not bad and the frequency band is correct, but the speed still cannot improve, then it’s time to look at the channel. This step is the answer to my family's second unsolved case.: At the same point, the speed dropped from 430Mbps to 180Mbps after 10pm, and then returned by itself during the day. At first, I suspected that during the evening peak hours of the operator, the desktop computer that could be plugged into the network cable ran up to 940 at the same time, which showed that the broadband was wrong. Later, I took a glance at the "WiFi Environment" or "Channel Quality" page in the router's backend to understand it.: The neighboring routers all lit up, and the number of routers on the same channel as mine increased from two during the day to eleven.

This problem is particularly serious on the 2.4G side, because it only has three non-combatant channels to choose from, 1, 6, and 11. Dozens of households in the entire building use them in turn, which is equivalent to more than a dozen people talking in a private room. The original intention of turning on "auto channel" on the router is to avoid crowds, but for many models, the time to select a channel is when restarting or in the middle of the night - if you scan a channel that is crowded during the day in the middle of the night, it will look empty and you will choose it as soon as the crowd comes back during the day, and you will be crowded with people all day long. In my house, the channel was automatically changed once at three o'clock in the morning, and it was changed to the neighbor's channel. The solution is very crude: Change the 2.4G channel from "automatic" to manual nailing. Take a look at the channel with the fewest people around and nail it. ； The 5G channel was also checked. The complete troubleshooting line for this "stuck at night", I'm here Six slow methods for symptomatic investigation It's in the evening rush hour, and the difference between it and pure broadband congestion is "how fast is the machine that plugs in the line?"

I believe there is something counterintuitive about this matter.: Signal strength is not affected by channel congestion. If eleven routers squeeze into one channel, your number of grids will still be full, because the number of grids is only "can you hear the router shouting", no matter how many people are shouting at the same time on the channel. Therefore, to find the channel level slowly, the only way to check the channel level is to scan the neighbor list in the background, and the number of grids cannot help.

The third murderer: The speed is indeed there, but it is taken away by the equipment.

There is another one that is slow at full speed. Checking dBm, frequency band, and channel are all normal, and the single speed test is also good, but it is stuck when a family is online at the same time. This is no longer a matter of the signal layer, but of the router. A router worth a few hundred yuan is rated to support dozens or hundreds of machines. That is a number that can be "connected", not a number that "every one can run at full capacity". Someone at home is casting a 4K screen in the bedroom, someone is playing games, and six or seven camera sensors are reporting separately. The air time on the 2.4G network is spread thin, and everyone has to queue up for their packages.

This real culprit was recognized after my family experienced an upgrade.: Back when the old router was used, the living room was full and the speed was fast, but at night the whole family would wake up and browse the web in circles. I wanted to add a signal amplifier for a while, but later on Counted 49 devices in the home That article made the calculation clear - the problem is not that signals are concurrency, amplifiers cannot save concurrency. The real solution is either to change to a router with a reliable machine, or it is simple and crude.: Draw a separate net for smart devices. What I did later was to convert the old router into an AP dedicated to feeding 2.4G devices. The main router was clear and clear, and only the mobile phone and computer were used. The main network was smooth that night. This disassembly method is as follows Move the camera sweeper to a separate WiFi There is a step-by-step wiring diagram. By the way, the machine will slow down falsely when it gets hot. During the summer, I took the router out of the gap in the TV cabinet and put it upright. Nothing was changed. The speed in the living room returned to 100 Mbps - I have also encountered this problem with other machines when it gets hot, so don’t take it seriously.

Check the order, it is easiest to follow this

Turn the above path into a sequential order, and don’t spend a penny on each step.:

• The first step is to look at dBm: Check the signal strength in the mobile phone WiFi details. -Skip this layer if it is within 60. If it is below -70, first solve the coverage problem, move the router or patch the node, and it will be useless to do anything else.
• The second step is to look at the frequency band: Check whether the mobile phone is connected to 2.4G or 5G in the router's background device list. Squatting on 2.4G, turn off the dual-band integration, separate the two networks, and manually connect to 5G.
• The third step is to look at the channel: Scan the neighbors in the background, 2.4G will nail the one with the least number of people on 1/6/11, don’t leave it alone.
• The fourth step is to test in separate pots: Let all the equipment at home be idle and test again individually. Whether it's fast when it's idle or slow when it's busy, it's not a matter of the signal. Check it based on the bandwidth and concurrency.
• The fifth step is to plug in the network cable and compare it.: The network cable is fast, but the WiFi is slow. Take advantage of the wireless part ； The network cable is also slow. That is a matter of broadband or optical modem. Speed ​​test posture Go with the old accounts for disconnection and troubleshooting.

Finally, remember the rules for measuring internet speed: When taking the test, don’t walk around the room with your phone in your hand. Stand at the spot and take the test before moving. ； Measure the same point three times, discard the highest and lowest values, and take the middle one. From now on, we will treat the grid number as an indicator light of "not connected". Whether the speed is good or not, let the dBm and the speed measurement number speak for themselves. After copying the point table at my house, I put it on the door of the weak current box. Check it again after half a year to see if the router has been moved or if the neighbor has added a machine. The numbers will give you the answer.