Second-hand Xiaomi AX3600 feeds 2.4G for 95 yuan, 40 devices are stable

The old AC2100 at home was converted into a dedicated wired relay IoT network, which I built two years ago.: Old machines use single-shot 2.4G specifically to feed smart devices , the main router was quiet. This structure had been peaceful until last month, when the Mijia App began to turn gray piece by piece at two or three in the middle of the night.: First came the speakers in the living room, then the sweeper, two lamps, a thermometer and hygrometer, seven or eight of them in one piece. There are always a few of the 40 or so smart devices that fail every day. Restarting them will make them better, and try again in another batch in two days. I press The order of the device offline section After arranging everything, the cloud, signal, and firmware were all eliminated, and finally it fell on the AC2100.: It's just too old. For 95 yuan, Xianyu bought a second-hand Xiaomi AX3600 and came back to take over.

Let’s first explain clearly what the AX3600 is.

AX3600 is the machine released on the same stage as Xiaomi 10 in February 2020. It is priced at 599. It is Xiaomi's first-generation WiFi6 flagship. Its full name also carries the words "AIoT Router". The selling points of those years are still relevant now.: Qualcomm IPQ8071A six-core chip, four CPU cores with two NPU network acceleration cores, 14nm process ； The memory is 512MB, which is exactly twice the size of the AX3000T still on sale. ； The 5G frequency band has 4x4 specifications, 2402Mbps at 160MHz bandwidth, and 2.4G is 574Mbps at 2x2. There is also an independent AIoT antenna responsible for discovering Mijia devices. The official nominal number is 248 units. I was stunned when I saw this number for the first time. It is almost double the nominal 128 units of the AX3000T.

We have to put our shortcomings out as well.: Three Gigabit LAN ports plus one Gigabit WAN port, no 2.5G, no USB. This is a rule in 2020 and cannot be changed. The official firmware has stopped updating a long time ago, so don’t expect security patches. Therefore, the current positioning of this machine is very clear - the hardware is good, the software is promising, and it is suitable for private network work.

Why IoT Private Network Needs WiFi6

Let me first explain my family background.: 62 devices throughout the house We have made great efforts to slim down, and about 40 of them are smart hardware such as light bulbs, sockets, sensors, and cameras, all of which are nailed to the 2.4G of the IoT private network. These devices have one thing in common - the traffic is pitifully small. A thermometer and hygrometer sends a few bytes per minute, but it has to speak. The 2.4G channel only allows one device to talk at the same time. The old rule of WiFi5 is that everyone queues up, one person per round. Even if each person with 40 devices only sends one sentence, the queue will reach the door.

OFDMA of WiFi6 changes this queuing mechanism.: Break a speaking opportunity into several small boxes and send out small packages with four or five devices at a time. I have written about the principle of OFDMA lane marking before , it was just a concept at the time, but this time it really happened - the more equipment and the smaller the package, the greater the revenue of OFDMA. My stall with 40 small packages happens to be its home field. The 2.4G of AC2100 is WiFi5. Without this capability, the air interface queue overflows during the middle of the night when devices report intensively. The router treats slow-responding devices as offline. This is the explanation for the waves of collective graying out.

There is still an account to replace the machine.: In terms of protocol selection, I have calculated the choice between WiFi direct connection equipment and gateway version equipment. , the Zigbee gateways in my home do not occupy space, and the remaining WiFi direct-connected devices are all frequent users of 2.4G. Giving this part to a new machine with strong 2.4G capabilities is the most appropriate way to spend it.

How to inspect second-hand items worth 95 yuan? Don’t touch the magic modified machine

The second-hand market of AX3600 has been very stable in the past two years. The price of Xianyu is 90 to 110 yuan, and the price of 120 yuan is normal if it is in good condition and comes with the original box. But the water in this price range is also deep.: Be wary of the ones that are twenty or thirty cheaper. There is one source of goods that is powered by OpenWrt or converted to RouterOS. Pictures of the seller will be posted soon. If you don't know how to flash your phone, don't get this freebie - the behavior of the flashed version is completely different from the official firmware you expected, and troubleshooting can drive people crazy. I only have one principle: Collect retired home machines that "have been using official firmware" and do not collect the remaining toss-and-play machines.

To test the machine, I stepped on it, five steps.: First, ask the seller if the firmware is officially used. If you are hesitant, don’t use it. ； 2. Turn on the power and check the lights. If the orange light turns to blue and stays on, it is considered normal startup. ； Third, turn over the bottom case to see if the SN sticker is there and whether there is any crack at the root of the antenna - AX3600 has seven external antennas, and it is a common problem for the root to be cracked during transportation. ； Four, log in 192.168.31.1 Take a look at the system status. If you can enter the background and the firmware version number is in the official format, then there is no big problem. ； 5. Ask if the power supply is original. This machine consumes a lot of power. If you just equip it with a brand-name adapter, it won’t be able to carry it for a long time. Inspection ideas for Redmi AX6000 received last time Also applicable, you can look at each other. No matter what the seller says when you get it, just do a factory reset first and then use your own account to bind it to Mijia. It will be clean.

Getting Started Setup: Wired relay, only sending 2.4G, copying the name

The wiring is reversed from other brands, and the incoming cable is plugged into the WAN port of the AX3600, which is the blue port - Xiaomi's wired relay rules are like this, AP mode article I have written about this pitfall specifically, so just copy it. Then 31.1 enter the background, common settings → Internet settings → working mode switch, select wired relay, and wait for it to restart. The management IP will drift after the restart. Don't panic. Go to the device list of the main router to find its current IP name. This is the step where novices are most likely to misjudge that the machine is broken.

Then three things. First, turn off the dual-band integration and turn the 5G switch directly to off - this machine is used as an IoT gateway and only transmits 2.4G. It is purely troublesome for 5G to collide with the 5G frequency band of the main router. The 4x4 2402Mbps is ignored. Second, the WiFi name and password do not change a word, copying the name of the old AC2100 IoT network. This is the easiest way to switch phones: The device recognizes the combination of name and password, not the machine. , with the same name, 40 devices can be switched seamlessly, and none of them need to be re-networked - anyone who has experienced it knows the pain of re-networking a sweeper. Third, the channel is manually nailed and staggered from the main router.: My main 2.4G router is at 6, and this one is at 11. An accident in which automatic channel hopping killed IoT devices in the middle of the night I touched it once and never dared to let it go automatically again.

After setting up everything, I took my mobile phone and connected it once to confirm that I could access the Internet. Then I powered off the old AC2100 and retired it. The entire switch took less than half an hour. Don't throw away old machines, clean them and put them in a drawer. The spare machine will always be useful one day.

Real experience after using it for a month

Let’s talk about the most concerning thing first: We all went offline in the middle of the night and haven't done it again for a month. The only time was when the speaker fell off in the hallway, and it recovered by itself after restarting, without connecting to others - this kind of single-unit accident had little to do with the router, it was because the device's own firmware was stuck. The change in response speed is more obvious than disconnection: When the Mijia App turns on the light, it used to turn on in a circle for a second or two, but now it basically turns on when it is clicked. This is OFDMA's aggregation of small packets at work. 40 devices no longer line up one by one, and instructions and heartbeats are squeezed into one train.

There is also a price to be paid. The power consumption is much higher than that of the AC2100. The big thing with seven antennas is plugged in all year round, and the electricity bill is more than ten yuan a year. I admit it. The 5G 4x4 is completely idle, which is a pity to be honest, but you can’t ask a 95-yuan machine to make full use of every antenna. As for those who want to use it as the main router - 512MB of memory and 248 devices are enough, but the firmware update does not have a 2.5G port. It will be reluctant to be the main router in 2026. My main router, AX3000T, has been used for two years. The state is still more reassuring. It also has a back-up path worth mentioning: The IPQ8071A platform is an evergreen tree in Enshan. The OpenWrt support is quite mature. I don’t want it to be used as an IoT gateway someday. Unlock SSH and flash third-party firmware It's okay to use it as a bypass router. This machine has much more room for gameplay than new machines at the same price.

Who is worth accepting and who should not be touched?

This machine is not suitable for everyone. I collected my thoughts for a month into a list:

Give a realistic decision-making sequence: Count the devices first. There are less than 20 smart devices. One person can handle all the main routers, so there is no need to buy them. ； If you have more than 30 units and are experiencing disconnection problems, consider getting one. Before buying, make sure the main router has a free LAN port. If not, add a switch first. After receiving the goods, follow the above five steps to inspect the machine. After receiving the goods, restore the factory, cut off the wired relay, send only 2.4G, copy the name, and stagger the channel. Complete the five steps and call it a day. If the budget could be relaxed to two hundred, I have written about how to choose between the three budget levels , the new AX3000T in production is much more worry-free ； The 95 yuan AX3600 is the price-performance ratio of "old flagship doing new work".