How many minutes does the WiFi freeze when the whole family comes home at the same time? It’s not that the router is broken, it’s that dozens of devices are crowding the same door

It took me half a year to figure this out. My home is set up with both working people and a baby. During the workday, the house is basically empty. The only cameras, sweeper base stations and a few sensors on the router are online. Every evening around 6:40, my wife gets home first, and I take the baby in with me at 7:15. It’s a difference of 20 minutes, so I’m fine. Last month, her workplace adjusted the shuttle bus, so we both took the same elevator upstairs - as soon as the door opened, there were three mobile phones, two tablets, and two laptops connected to WiFi, and everything was buzzing within a few minutes after entering the door. That night, my son wanted to watch cartoons. The TV was spinning in circles for more than a minute. My mobile phone and WeChat could not show any messages. My wife casually said, "Is the router going to need to be replaced?", which made my heart skip a beat.: The router is an AX3000T and has only been used for a year and a half, so it’s not that bad.

Afterwards, I checked the backend of the router and looked at the logs of several smart device apps all night. I took apart those few minutes and found that the root cause of the problem had nothing to do with the newness of the router. it's called instantaneous concurrency ： Normally, the devices at home wake up and connect in batches, but in the scenario of "the whole family arrives home at the same time", the "three-piece power-on set" of dozens of devices is forced into the same minute. No one on this site has written anything about this angle.—— Six types of triage for slow Internet speed It’s about the long-term classification of “slow”. Actual measurement of machine capacity It's about the number of units and the water level, and it doesn't care about the instantaneous thing of "squeezing the door in the same second". This article will lay out what I took apart that night.

In the few minutes you walked in, every device was doing the same thing.

Let’s first explain a few things you need to do to connect your phone to WiFi. Your mobile phone is still connected to the data in the elevator. As soon as you enter the door and search for your home WiFi, it will initiate a connection, handshake, and authentication. This is the first set of actions. ； After connecting, it asks the router for an IP address, which is DHCP. The router checks its own address pool, assigns an IP, and writes down the lease. This round trip takes several seconds. ； It is only when the IP is obtained that it is truly "online", and then all the things in the background of the system wake up - WeChat reconnection, mailbox push notification, photo album cloud synchronization and activity detection, and the App's message channels are connected one by one. This is not over yet, the sensors at home are also joining in the fun: The human presence sensor detects "someone coming home" and triggers automation. The lighting gateway and air-conditioning partner come online to report one by one.

This process is done one by one, and the router is stress-free. The problem is that when "the whole family arrives home at the same time", three mobile phones and two tablets start running this process within the same ten seconds. The laptop starts up and catches up, and the smart devices come online collectively following the automated instructions. Each one looks normal when viewed individually. When stacked in the same time window, it becomes a peak wave of routers. I later saw the CPU curve that night in the background. It was usually in the single digits. In those few minutes, it was directly above 80%. After seven or eight minutes, it dropped back. It was not broken, but squeezed.

My family’s actual test account: What happened during those few minutes when I was stuck?

It’s meaningless to just talk about the mechanism. Show me the evidence from that night at my house. In the background of my router, I can see the number of connected devices and the load curve. I took out the screenshot of the evening period.:

20 devices came online collectively within seven minutes. What does this speed mean for the router? The article about measuring with a machine As I said earlier, the pressure on routers is not the number of routers, but "the number of routers multiplied by the number of connections multiplied by the traffic volume." The number of devices tripled in two minutes, and the number of connections was even more daunting—as soon as the phone woke up, background services such as WeChat, push notifications, and cloud synchronization had to establish dozens of connections, and one phone easily accounted for two to three hundred sessions. I later specifically looked at the conversation list. In the few minutes after the whole family arrived, the number of conversations increased from about 300 in standby to nearly 2,000. This number is nothing to a desktop router, but a home small box CPU has a single core or a dual core. Forwarding, table lookup, and WiFi transmission sequence are all queued up on these two cores. When the instantaneous peak hits, the TV traffic at the end of the queue is stuck - this is the direct reason for the baby cartoon to spin in circles.

There is also an invisible one: DHCP. There are many standby devices at home, so I set the address pool to 50 at the beginning. That night I saw a mobile phone that took IP three times before it was successful. The reason is that DHCP is a "first come, first served, broadcast call" mechanism. Twenty devices call at the same time, and the routers respond one by one. The ones that call more closely will be squeezed out and try again. I'm not afraid of trying again. What I'm afraid of is that during the retry, the device is "connected to WiFi but not connected to the network." If the signal is full and nothing can be generated, the experience is laggy. This kind of card has nothing to do with bandwidth - I tested the speed that night, and when everyone was there at 8:30, it came out to over 900 Mbps, which shows that there is no problem with the line, and the card is only stuck on the "entry tax" for those few minutes.

Why the evening rush hour card and the entrance card are two different diseases, don’t mix them up

This step is the easiest to get confused, and I made the mistake at first. The entrance card is a matter of the family, and the evening peak card is mostly a matter of the outside. There is only one way to judge.: The time for checking the card is not aligned with "people entering the door" .

At nine o'clock in the evening, the whole family started to watch their own videos and started to get stuck. It was due to area congestion or channel collision. Six slow ways The section on time-based triage is very detailed. Comparing the mobile phone traffic with the same video can lead to a conviction. The law lies in the router channel and the operator. The characteristics of the entrance card are very distinct: It's just "five to ten minutes after opening the door", when all the devices at home come online. After this window, I'll be fine. It's never okay to go home alone during the day. My family's conviction that night relied on this time alignment - the starting point of the lag was precise to the minute we walked in. This was not something that could be caused by a fault in the wiring.

The treatments for the two diseases are completely opposite. You can apply for repairs, change operators, or change broadband for your access card, but it won’t do anything for you. ； Even if you adjust the equipment arrangement at home during the evening rush hour, it will be in vain. If you make a clear distinction before taking action, you can save a lot of wasted money.

No need to change equipment, just use these four tricks to smooth out the first few minutes after entering the door

After figuring out the principle, it costs zero to cure this problem, and the core idea is just one word: Staggered peak . If the action of squeezing the door is broken up at the same time, the peak value of the router will naturally collapse. I'll rank them in order of effectiveness.:

The first step is to fix the IP to feed the resident device. For devices such as cameras, base stations, and TVs that never leave the house, bind static IPs or DHCP reservations to them in the router. They do not participate in grabbing addresses, the instantaneous pressure on the address pool is directly reduced by half, and these devices will no longer be disconnected and reconnected every now and then. I have 14 tied up at home, and this is the most direct and effective method.

The second trick is cloud synchronization and peak shifting. The default behavior for automatic backup of mobile phone albums and network disk synchronization is "upload as soon as the network is connected". Several mobile phones are uploading photos at the same minute, and the uplink bandwidth is completely full. Is the video card stuck when I click on the TV? Card. Change the backup of your family's mobile phone photo albums to "only when charging" or set alarm clocks for staggered times. This will free up a few minutes of walking when you enter the door. My family's current rules are that my baby's tablet backup is scheduled at 11 o'clock at night, my wife's backup is scheduled in the early morning, and mine is scheduled to be backed up manually.

The third tip is, don’t use “someone comes home” as a trigger for the automation of smart devices. The human body sensor detects a person and triggers all the equipment in the house to come online. This adds another dimension to the "door-in storm". If you can change it to "door lock open" and trigger it alone, change it. The door lock is a single event, and the lights and air conditioners follow a single command. It is much gentler than "waking up the whole room when a person is detected". My entrance light used to be triggered by the presence of the human body. After it was changed to be triggered by the door lock, the list of online devices when I entered the door was shortened.

The fourth trick is to leave a priority channel on the router side for devices such as TVs that are “used as soon as you enter the door.” Many firmwares have QoS or device priority, setting TVs and set-top boxes to high priority. After entering the door, others are slowly synchronizing, the traffic on the TV jumps in the queue and leaves first, the baby's cartoons are not spinning, and no one at home complains that the network is broken. This is a temporary solution, but it’s really about “experience”, so it’s worth it.

Under what circumstances do you really need to move the equipment? A table explains it clearly

The previous ones are all zero-cost adjustment methods, but the boundaries must be clarified—when does the fault really point to the device itself? I wrote the judgment line into a table:

The core of judgment is one: The instantaneous card is "Peak" and the long-term card is "Water Level"」 . High peak value and low water level can be cured by shifting the peak value ； The water level itself is close to the upper limit. If the peak comes again, it will overflow the embankment. Then it will be the turn to change the machine. My AX3000T is still running smoothly, but after the peak shift, there is no such thing as a door card anymore. I really need to check the water level in my home. Actual measurement of machine capacity That article has a complete guide on how to watch the backstage.

ending: Check yourself in one minute to see if your home has this problem.

This problem is usually completely invisible and only occurs when "people are together", so many families are not even aware that they have it. Self-examination is simple: In the evening, after the whole family got home and started using the Internet, they stared at the watch to see if there was a "connected but unable to swipe" card within ten minutes after entering the door. After that, it would recover on its own. Yes, that’s what this article is about ； No, congratulations. You don’t have many devices at home or the peak is naturally off-peak.

If you really want to do it, just copy the order.: The resident device is bound to a fixed IP, the mobile cloud synchronization is staggered, the trigger is automatically changed, and the TV is prioritized. It only takes one night to complete all four things. In exchange, no one will shout "the network is broken again" in those few minutes every evening. Finally, let me be honest: When it comes to your home network, most of the time it's not that the equipment is broken, but that everyone's life rhythms overlap on the same timeline - disconnecting the cables is more effective than replacing the router.