The price of Xiaomi router Gigabit dropped to just over 200, and three of the real culprits are still stacked on top of each other

Last Wednesday at eight o'clock in the evening, there was a collective strike at home: The TV was spinning in 4K, my wife’s short video was stuck for three seconds, and the video call in my mother’s bedroom was stuck in a slideshow. I have been using AX3000T for Gigabit broadband for two years ( I wrote about it after two years of actual testing ), the mobile phone can usually run 680 MB in the living room with 5G. When I tested it that night, it was 230, which was sometimes fast and sometimes slow. The first reaction was that the broadband in the area was having trouble, and the call almost reached 10,000. After thinking about it, I decided to investigate it myself first. After two hours of investigation, I found that there were three real culprits, and they were all stacked on top of each other. None of them were faulty routers.

first step: Take five minutes to figure out which section is slow.

The most taboo thing about slow internet is restarting or changing settings as soon as it starts. My habit is to first plug in the network cable with my laptop and measure the speed from the LAN port of the router. This step can directly eliminate most of the suspicion. The computer plug-in cable shows 935 MB, indicating that the wired segments of broadband, optical modem, and router are all clean, and the problem is locked in the wireless segment and equipment segment. I unplugged the same computer, sat in the living room and connected to WiFi and tested it again, 230 MB, sometimes fast and sometimes slow.

In addition to which section to measure, we also need to first identify “who is slower?”: Slowing with the whole family and slowing with only one device are two different things. The third line in the table is the hook left. If you are too lazy to turn on your computer more often, you can also check the real-time speed of the entire broadband in the Mijia App. It only takes 30 seconds for a person to check whether the uplink and downlink are full from the sofa. If you plug in the network cable and test it, it is only 100 or 200 Mbit/s. That is a job on the broadband side. Check the light attenuation, optical mode port, and operator one by one. I have written about the four-layer investigation , not repeated here. There is also the posture of the speed test itself - turn off the background that steals traffic before the test, which tool is accurate to use - if it is not correct, the router will be wronged. Let’s read the speed test article first Do it again.

The real murderer: Uplink was eaten by my mother’s cell phone

If the whole family is stuck together and the TV is the first to suffer, 90% of the time it's not the router that's to blame, but the uplink. My Gigabit broadband is 940 Mbps downlink and only 50 Mbps uplink, which is usually enough, but the bad thing is that it will be completely taken up by one device. What can the upside drag down the downside? When downloading, TCP needs to send a confirmation packet back, and the return path is blocked, so the download speed still slows down. I wrote about this in the speed test article. The TV's ability to pull 4K streams depends most on the confirmation packet, so it is always the first to circle. It looks like the broadband is broken, but it is actually the return trip that is blocked.

Open 192.168.31.1 , each device in the device list on the homepage has a real-time rate. At a glance, the upload of a HUAWEI mobile phone cannot move at 5.5MB/s - converted to 44MB, it consumes nearly 90% of my 50MB uplink. Click on it and see it's my mom's. She came to stay at my house for a week. The Huawei cloud library automatically synchronized with Wi-Fi by default. There were two years of photos and videos stored in the phone. There were 19 gigabytes left in the synchronization queue. It would take more than an hour to run at full speed of 5.5MB/s. During this more than an hour, the whole family had to be with the card.

There are two levels of practice. Now let’s set the device-level speed limit for that mobile phone. The upload speed will be reduced to 2 MB and the download speed will not move. You can set it on the device details page in 31.1. The speed limit article has the complete path . In less than a minute, the 4K TV stopped spinning, and the 5G in the living room returned from 230 to 410. The long-term plan is on her phone: Settings→Huawei Account→Cloud Space→Gallery, turn off "Gallery Data Synchronization", or change it to manual connection. It would have been possible for her to isolate the guest network by one layer, but the old man found it troublesome to switch back and forth, so it was easiest to just turn off synchronization. How do you usually catch this kind of stolen traffic in the device list? The article about capturing traffic is written in more detail. .

The real murderer two: The nailed channel was crowded by the neighbor's new machine.

After finishing the upstream training, the video in my mother’s bedroom still paused every few seconds, and the sweeper even dropped offline once that night. Both symptoms point to 2.4G. Install a WiFiAnalyzer on your Android phone and scan it around: The 2.4G router on my main router has long been stuck on channel 1 - before, the channel automatically jumped to 12 in the middle of the night, and the sweeper camera collectively lost contact once. After that I nailed it manually. ——As a result, the neighbor's two newly installed broadband routers' automatic channels were all on 1. Three signal pillars were stacked in a grid, making it difficult for anyone to escape.

2.4G has a total of three channels 1, 6, and 11 that do not fight with each other. Just because you nail it down does not mean it will be settled once and for all. The pattern will change at any time if your neighbor installs a new machine or changes the route. The channels on the 5G side basically do not overlap with each other and cannot be squeezed. Just worry about 2.4G. Comparing the scanned pictures, 6 was the most empty that day, so I moved the main router to 6 ； The old AC2100 of the IoT private network is sitting on No. 11, and it is still separated from the main router. Don't copy my numbers. Leave your blank blank and look at your own scan of the day. By the way, my mother's bedroom is the farthest away from the main router, and her mobile phone can only capture 2.4G. When the channel is crowded, she is the first to suffer. A room with a weak signal will amplify the congestion. This is an illusion caused by the overlap of two problems.

The night after the modification was completed, the video in the bedroom went smoothly and the sweeper never dropped offline again. Regarding trust, I suggest you scan it once every quarter, just like doing a physical check-up on the network. I have written the physical examination checklist by cycle. .

The third murderer: The network installed on the TV is slow

After the first two repairs, the 4K TV still occasionally spins twice. I almost thought it was the fourth problem. Looking back at 31.1, the real-time rate of the TV is not at all full, and the signal -52 is also good. Later I discovered something was wrong - the TV menu was also stuck, and it took two seconds to open the settings page. This has nothing to do with the network, it's the TV system itself that's stuck. Turn off the power for 30 seconds and then turn it on again, Transit will be fine.

This TV has not been restarted in half a year. Smart TVs have the same behavior as mobile phones. The more the memory is used, the more it fills up. The jamming is most like a slow Internet connection. Therefore, this step must be left to check the network speed.: Distinguish whether it is "slow network" or "slow device". The menus are all spinning. Restart the device first, don’t mess with the router. Writing about TV networking I also mentioned this division when: The buffer circle is the network, the picture frame is the decoding, the menu card is the system, and there are three types of cards and three diseases.

Three suspicions that were easily eliminated

In real investigation, it is impossible for every suspicion to be true. I eliminated three easily this round.

Cengwang: There are 66 devices in the list. Click on one device to check the online time and MAC manufacturer. They are all self-made devices. They are clean. How can you check what I wrote on Cengwang? . Amount of machines: 66 units are far away from the AX3000T's nominal 128 units, and the memory usage is just over 60%, which is not a bottleneck. 62 Taiwan big weight loss article There are benchmark numbers. fever: I touched the outer shell and found it was warm and not hot. Compare it to the grades I measured with a temperature measuring gun. , 41 degrees is normal. There's another one for free: My home's scheduled restart is set at 4 a.m. every Wednesday. It had just automatically restarted on the morning of the incident, and it lasted 16 hours. It was not even considered suspicious.

Half the fun of troubleshooting is troubleshooting. If it feels hot to the touch, or if the number of devices exceeds one hundred, it is another disease. The fever article There is another set of rules.

The completed bill and the order of copying

After the repair, I retested at noon the next day. The 5G in the living room returned to 680. I tested again at 9pm during the evening rush hour to 655. If it dropped less than 10%, it was considered normal. Looking back, none of the three real culprits would be fatal if taken alone.: The uplink was taken up by 44 MB, the three channel pillars were stacked on one grid, and the TV memory card was stacked together to reduce the Gigabit limit to 230. This is the trouble with troubleshooting network slowness. If you think about a single symptom, you will always be one level behind.

Copy in order: Plug the computer into the network cable and lock the segment. Check the 31.1 device list to see who is uploading it. Scan the picture to change the channel. Restart the device itself that is stuck. Scan again next quarter. If the router is not broken, just do a factory reset. Mine reboots itself every Wednesday at 4 a.m. and it has been stable for two years. Another habit to prevent fooling around: When guests come to your home for a long time and new equipment is added, it will be faster to take a look at the upload column of the equipment list on the first day than to second-guess it. 90% of network slowness is caused by superimposition, layer by layer, which is much faster than guessing.