The speed difference between two mobile phones on the same WiFi is more than 100 megabits? It’s not that the router is biased, it’s that these five places are different.

This incident started at the end of last month. I have Gigabit broadband at home. I measured the speed in the living room and the phone got 620 Mbit/s, which I was quite satisfied with. My wife took it and tested it on her mobile phone. It was 480 MB. Her first reaction was that I secretly limited her speed. My first reaction was that the router was broken. The two of them took four or five rounds of measurements, and both stood in the same place. The numbers were steadily different by more than 100 megabytes, and no one could convince the other.

That night, I took out the two mobile phones and compared them. I also borrowed my mother-in-law's mobile phone and an old tablet to join in the fun, and I finally figured out the matter. The speed measured by two mobile phones under the same WiFi is different. 90% of the time it is not because the router is biased, but because the two mobile phones themselves are different. This article explains the five sources of the gap one by one and teaches you how to judge.: The difference is considered normal, and the difference indicates there is something wrong with that phone.

Let’s talk about the conclusion first: The difference between the two mobile phones is from tens of megabytes to one or two hundred megabytes, which is normal.

Many people have a default idea: The same WiFi should measure the same speed. The idea itself is untenable. WiFi does not mean that the router "distributes" the speed to the mobile phones. Instead, each mobile phone shakes hands with the router and each has its own agenda. The negotiated gear is determined by the mobile phone's own wireless hardware. If the hardware of two mobile phones is different, the gear will be different, and the speed will naturally be different.

This set of actual tests in my hand: I bought my mobile phone the year before last. My wife’s phone was more than a thousand dollars cheaper, and my mother-in-law’s phone was a mid-range phone three years ago. Three units were placed on the same coffee table in the living room for testing, and the results were 620, 480, and 290 MB respectively. The old tablet is the worst, with only 86 MB - it only supports the 2.4G frequency band, which is not on the same track as others.

So set your expectations first: The difference between the two mobile phones is 20% to 30%, which is a normal hardware difference. ； If the difference is more than half, it is worth checking further. The 140MB gap in my home was finally found to be due to two reasons. One cannot be corrected, and the other I easily corrected. Let’s talk about it one by one.

first gap: Number of antennas, invisible configuration table of mobile phones

Router promotions always say "4x4 antenna". Mobile phones also have this parameter, but few people see it. This number refers to the number of transceiver channels of the mobile phone wireless network card, which is called spatial stream in jargon. A 2x2 phone has two streams, and a 1x1 phone has only one stream. The number of channels directly determines the ceiling: For the same WiFi6 and the same bandwidth, the theoretical range of 2x2 is exactly double that of 1x1.

my family situation: My mobile phone is 2x2, and my wife’s phone is 1x1. This is doomed to mean that her unit is naturally about half slower, 480 vs. 620, which is actually considered to be a good performance on her unit. This gap cannot be smoothed out through any settings. It was determined the day you bought the phone. The manufacturer's promotional page usually does not directly state whether 1x1 or 2x2. You have to go to the "spatial flow" in the parameter page or the disassembly report. There are cases where the antennas of the same model are different, so you can only check one more step before buying.

How can you roughly determine how many streams your phone has? Look at the "Connection speed" on the WiFi details page.」: Under WiFi6 and 80MHz bandwidth, 2402 MB is 2x2, and 1201 MB is 1x1. You can see it most accurately when your phone is pressed against the router. The origin of this "connection speed" and why it is never satisfied, I am Three accounts of bandwidth negotiation rate and measured speed I broke it down in that article, so I won’t repeat it here.

second gap: The two mobile phones support different WiFi generations.

Phone support for WiFi algebra varies widely. WiFi5 mobile phones only have a maximum negotiated range of 866 MB, WiFi6 can reach 1201 or 2402, and WiFi7 is even higher. My mother-in-law’s mid-range phone from three years ago has WiFi 5. The theoretical ceiling is 866, and the measured 290 MB is not unfair at all.

What is more hidden is "different generations of the same generation". They are all called WiFi6, some mobile phones only support 80MHz bandwidth, and some support 160MHz. ； Some support 2.4G and 5G, and some also have multiple 5.8G. The router will automatically negotiate with each mobile phone the highest speed they can accept. The results of the negotiation will be different, and the speed will be different. I've also gone in the other direction of this matter.: Old equipment will drag down new mobile phones. A device that only supports low-speed gears will occupy the empty space and talk slowly, and the share of new mobile phones will be diluted. This pitfall is What’s the problem with slow internet speed at home? There are specific troubleshooting methods in that article.

There is also a classic pit related to dual frequency: One phone is nailed on 2.4G and the other is on 5G. The difference between the two frequency bands is ten times, which is how the 86 MB of my old tablet came about. You can see which frequency band you are currently connected to on the mobile phone WiFi details page. If there are two mobile phones, one is 2.4G and the other is 5G, you should first resolve the frequency band issue before talking about anything else. The dual-band-in-one switch in the background of the router and the smart switch on the mobile phone side can secretly push the old phone to 2.4G. I turned off the "smart switch" on my mother-in-law's phone and manually designated 5G, and the speed increased from 290 to 410 MB.

The third gap: The grip, mobile phone case and human body are all antenna killers

This is the most easily overlooked and most easily wronged router. The antennas of mobile phones are generally arranged on the top and bottom edges of the fuselage. When holding the mobile phone horizontally to play games, the palm of your hand just touches the antennas. ； When measuring the speed vertically, the numbers can differ by tens of megabytes depending on the position of the fingers and the tightness of the grip. When I tested my wife's phone, she habitually held it with both hands, and I held the frame with one hand. This single action alone resulted in a difference of more than 30 megabytes. Later, we put the mobile phones flat on the coffee table, with the screen facing up, and stepped back one meter before pressing the variable.

Mobile phone cases also contribute. Mobile phone cases and magnetic cases with metal brackets can effectively attenuate 5G band signals. When I tested my wife's phone, she wore the magnetic case. After taking it off, 480 changed to 520, which is an increase of 40 trillion. Not all cases are so harsh. Plastic and silicone cases are basically insensitive, and those with metal parts are the most damaging. Take off the shell before measuring the speed. This is not metaphysics, but physics.

「People themselves are also obstacles, and their bodies containing water will greatly attenuate 5G signals. If two mobile phones are tested at the same time, and one is in the person's hand and the other is on the table, the results will be unfair. Therefore, the rules for comparing the speed of two mobile phones are very simple.: Pick the shell, place it flat, in the same position, and move away. Measure three times to get the median. The rules are unified, and the difference is the difference between the mobile phones themselves.

The fourth gap: The software status is different and the background is running secretly.

At the moment when the speed is measured, what the phone is doing in the background will directly affect the results. If one phone is automatically backing up its photo album and the other is idle, the former will measure low. Of the 140 gigabytes gap in my home, quite a bit is due to the automatic backup of my wife's cloud photo album with more than 30 gigabytes slowly creeping up in the background. After turning off the backup and clearing the background, her channel increased from 480 to 560.

There are also several software-side variables: The power saving mode will push the wireless network card into a low power consumption state, and the speed will drop a bit. Make sure it is not turned on before measuring the speed. ； Some mobile phone systems will limit WiFi performance when the screen is off. The screen-on test and the screen-off test are two numbers. ； The old mobile phone has been saved for two or three years and has not been restarted. The wireless driver status will also fluctuate. Restart it and test again. These are not the router's business, but the mobile phone's own business.

By the way, there are formal methods to determine "who is secretly occupying bandwidth": The device list in the background of the router can see the real-time traffic of each device. I used it to catch my computer secretly accessing the network disk in the middle of the night. That article Six slow methods for symptomatic investigation I also wrote about it. Before comparing the two mobile phones, take a look at this place to rule out background sneak peeks, so that the compared numbers will be clean.

The fifth gap: The speed measuring posture itself is not aligned

The fifth source has little to do with the mobile phone itself, but a problem with the comparison method. The correct posture when measuring speed is more demanding than imagined: Node selection, speed test period, single or multiple times can confuse the results. If the same speed test App assigns automatically assigned nodes to two mobile phones in different computer rooms, the results will be incomparable. The first time I tested my wife's phone, the App assigned it a cross-provincial node, and the numbers were ridiculously inaccurate. Before speed testing, manually lock the two mobile phones to the same local node. This is the bottom line. I have the specific speed measurement posture. How to measure broadband speed accurately I wrote the complete version in that article, including how to choose tools, what to check before taking the test, and what numbers are considered inadequate. Just follow them.

The time periods also need to be aligned. Gigabit broadband during the evening rush hour and early morning are two completely different worlds. If the two mobile phones are tested three hours apart, it is not a comparison but a chance. Also, don’t take the single number as a conclusion. The same mobile phone can be different by 30 to 40 Mbps when measured twice every ten minutes. Compare the two mobile phones at least three times each and take the median, otherwise there will be no end to the quarrel.

How to tell which phone is really slow?: A check list

After talking about the five sources, give a cheat sheet. How much is the difference, where to look, and at every turn, it is clear at a glance:

After checking in, the order of processing is also particular. Zero cost first: Repeat the test in the same speed measurement posture (same node, same position, shell removal, background clearing), and many "gaps" will be narrowed on the spot. Look at dual frequency again: Are the two mobile phones on the same frequency band? The one nailed to 2.4G must be manually moved to 5G. The gap between these two steps is more than half, which is basically the hardware generation difference, such as 1x1 vs. 2x2, WiFi5 vs. WiFi6, which belongs to the "thousand yuan difference when buying a mobile phone back then", and the router cannot save it.

There is also a reminder in the opposite direction: If two mobile phones usually have about the same speed, but one of them suddenly crashes a lot recently, it's not a hardware generation difference, but a malfunction. This kind of single-machine problem that "the whole family only has one machine is slow", I have troubleshooting methods here My phone keeps disconnecting from WiFi automatically As written in that article, the idea is to first doubt the software status of the phone itself, and then doubt its wireless hardware. The hardware generation gap has always been the case, and the sudden slowdown is just a recent problem. Don't confuse these two things.

Ending. After my wife’s phone turned off the cloud photo album backup, took off the magnetic case, turned off smart switching and manually connected to 5G, the speed measured in the living room was around 560 Mbit/s, which was 60 Mbit/s behind my 620. This is the normal level of the hardware gap between the two mobile phones, and she no longer said that the router was biased. As for my mother-in-law’s old 290 MB WiFi 5 machine – it’s enough to stream videos, but it doesn’t move anymore.