How do you set the Xiaomi router's AP mode? The old AC2100 uses wired relay to feed 14 smart devices; if you can't get into 31.1, don't rush to reset
two years ago, after switching the main router to AX3000T, the retired AC2100 sat in a drawer gathering dust for half a year. The turning point was one late night when the vacuum went offline and two cameras went down, and the Mijia app's alert was flooded with half the screen—the root cause was too many old devices on the 2.4G screen. I dug out this old machine, converted a network cable into an AP specifically to feed smart devices, and from then on, 14 devices were secure. This article explains the modification methods, pitfalls encountered, and which features fail all at once.
first clarify: what exactly is that "wired relay" in the backend for
Xiaomi backend operating modes, there are three options: router mode, wireless relay, and wired relay (some firmware uses wired access). Router mode is the default posture: dial by yourself and send house numbers to the whole family; Wireless relay is a wireless relay when there is no network cable, cutting the speed in half. I previously wrote a full article about AX3000T to supplement kitchen signals, the wireless relay article ; Wired relay is the main focus of this article. There are all kinds of online terms: AP mode, wired access, and using as an AP—all are about it.
| Mode | Who Dials | Network | Speed | Who Suits |
| Routing Mode | dial | my own portal | go full speed | the only main router at home |
| wireless relay | main router | the same network segment | it is halved and discounted again | without network cables, Only wireless relay |
| wired relay | main router | the same network segment | basically no discounts | you can get through with a network cable to get through |
switched to wired relay, this machine was left with only two jobs: delivering WiFi and acting as a switch. Tasks like dialing and issuing address numbers are all returned to the main router, which itself receives an IP from the main router and resides on the same network. So the whole house is still a single network, so screen casting, NAS access, and device cross-border access are all unaffected—this is completely different from Tenda's WSP model, where WISP sets up its own network segment, and casting the screen can't be found. I've fallen into that trap, which I wrote about in the of Tengda's bridge .
my three-step modification: plug the network cable into the WAN port, not the LAN port
first talk about the most common mistake: where to plug in the wire. When Xiaomi switches to wired relay, the network cable from the upstream needs to be plugged into WAN port, which is the blue port. This is the exact opposite of Mercury Tengda's general method of "LAN to LAN, then manually turn off DHCP." The first time, I stuck to the old habit of plugging in the LAN port, but no matter how I tried to switch it in the background, it always showed failure, so I thought the machine was broken. Later, I only figured it out after checking the official documentation. If you want to see the general manual modification principle, the article on using router as a switch, but don't copy Xiaomi devices—switching with their own mode is much easier. AX3000T this new machine with four ports full Gigabit, WAN, and LAN adaptability, it doesn't really matter—it's up to you to choose whichever you plug in.
the specific steps are three: First, power the AC2100 and connect your phone to its WiFi. The initial name is usually the one starting with "Xiaomi Router," or a name you have changed before; 2. Go to 192.168.31.1 in your browser and enter your management password; 3. Find 'Internet Settings' under 'Frequently Used Settings'. Some firmware versions are called 'Working Mode'. Select Wired Relay, click Save, and wait a minute or two for it to take effect. The Mi Home app also has an entry point. In the toolbox's routing settings, you can find internet mode, but the phone must be connected to the router's WiFi to switch devices. After a long search, it's not as straightforward as the webpage backend.
Before
save, think carefully about the WiFi name. You can also have it send the same name and password as the main router, but that's not roaming. The phone sticks to the weak signal and won't let go. The switching pitfall is roaming stickiness article. My approach is to name each individual. Why I choose them separately will be explained later.
first pitfall: After saving 31.1, you can't get in, but it's not broken
The day after switching the
mode, I wanted to go in and change the channel, but entering 192.168.31.1 just wouldn't open it. The blue light stays on, the device is fully online, everything is normal, but the background can't be accessed. My first reaction was that the machine was malfunctioning, and I almost long-pressed Reset—absolutely not. The reason is simple: it no longer issues its own address numbers; it manages IPs and switches to master route assignments. For example, if it is assigned to 192.168.31.80, the old 31.1 will naturally be empty.
there are three ways to get your new address number. First, log in to the router AX3000T's backend, check the device list, find the device with AC2100 in its name, and the IP address after it is the new address; The second method is even easier: tap this router in the Mi Home app or Xiaomi WiFi app to go straight to the management page, no need to remember the IP; The third option is a last resort: long press Reset to restore. If you don't have any specs, you'll have to redo it. Binding Mi Home is for nothing, and I'll calculate the cost in this post the factory reset .
I later added a safety net: I bound it to a static IP in the main router backend, so from then on it fixed an address, so I no longer had to search the device list to find it. The binding operation was the article on static IP binding. Here's another lesser-known trick: Sometimes you can access the backend, but the page only has the relay status and you can't see any other settings. Change the apsetting in the address bar URL to setting and press Enter, and the full settings page will appear. This trick isn't available on the official website—I dug it up on a forum.
second pitfall: these switches are just decorations in AP mode
after changing the mode and checking the backend, you'll notice some settings turn gray or disappear altogether. It's not broken, it's that the work has been moved. Since both dial-up and NAT are moved to the main router, settings related to "outside the door" naturally need to be done on the main router:
| Settings Item | AP Where to Set | |
| Internet Access Settings (PPPoE Dial-up) | grayed | main router |
| port forwarding, UPnP, DMZ | invalid | main router, The principle is that the VLAN binding |
| IPTV in the port forwarding article is invalid | IPTV recognize the main router network | |
| WiFi name, password, signal strength | commonly used | all set on this device to |
| scheduled restart, Commonly used hidden SSID | photos | set up a black/white list of |
| devices on this device | and you can control wireless hacking | Right on this platform |
the most confusing among these is UPnP. An old device was connected to the AC2100, and no matter how I tried to open UPnP in its backend, it wouldn't work. Later, I realized: it doesn't even manage the door itself, and even if you write a note to open the door, you can't send it out. Where to open UPnP and what to do when it is enabled, article UPnP detailed in detail. The main path to port forwarding lies in the between port forwarding and DMZ. Remember this sentence: when you go out, find the main router; only the small plot inside belongs to this AP.
my approach: single 2.4G as an IoT private network, the main router is quiet
back to the night at the beginning. All 14 smart devices in my home use 2.4G slow modules, squeezed onto the same 2.4G main router as my phone, so there's only one channel for nothing. The old devices speak slowly and take up a long time, while the phone spins in circles while swiping. I calculated this AirTime cost in the about slowing down WiFi on old devices. So after changing the AC2100's AP, I didn't have it send the same name as the main router, but instead sent a separate 2.4G line, with an IoT word after the name. The camera, speakers, sensors, and vacuum cleaner were all nailed to this network, and the main router's 2.4G and 5G were mostly quiet. The complete slimming record of 62 devices is in the article on with the number of devices.
both machines send 2.4G, the channels must be manually staggered: AC2100 is fixed at 1, and the main router is set at 2.4G at 11. Don't turn on the automatic channel, it automatically jumps. The batch ESP8266 of old modules in the vacuum cleaner's camera only recognize 1 to 11. I experienced the mass loss of contact in the middle of the night, which I wrote about in the of the channel. As for how to separate the 2.4G and 5G models and what to name them, the details can be found in the article on the dual-band . There's another benefit after this upgrade: if smart devices disconnect, the troubleshooting scope is cut in half. First, check if the AC2100 is powered off, then check if the channel trips. The full order is in the article on Mijia device offline troubleshooting.
someone asked why they didn't just build a mesh directly. First, the AC2100 generation doesn't have a Mesh networking button in its firmware and isn't on the supported list; Second, Mesh sub-routers emphasize unified management and whole-house roaming. My task is to isolate slow devices so everyone does their own thing. If you want the whole house to switch automatically under one name, look at Mesh networking —that's a different path.
want to change the routing mode back: two main routes, one last resort
changing back is easier than changing the old one. Route 1: Use the recovered IP to log in to the background (for example, the one with a static IP is a fixed address), switch between common settings, internet settings, and working mode, select normal mode, save and restart, and it will revert to a router that can dial by itself. 31.1 will also come back as well. Path 2: If you can access the backend but can't access the entry, use that trick to modify the URL, change apsetting to setting, and the settings page will appear. The worst option is to reset: lose all configurations, switch back to routing mode, then redo the broadband account, WiFi, and Mijia binding. Before you start, copy down your broadband account and check the account information this article.
there's another tip: machines that have already combined Mesh with the main router can't switch to relay mode in the backend, so you need to unbind the Mesh before you move, otherwise the options will be grayed out and you'll waste your time.
Wrap up with a selection order. If you have a network cable, want to add more ports, or isolate slow equipment, use a wired relay AP; If there is no wiring and only wireless relay is possible, use wireless relay to accept speed discounts; If you want auto-roaming with a single name throughout the house, use the same brand Mesh; If you just want a few more LAN ports and don't need WiFi, you might as well turn off the wireless and use it as a switch. My answer is two devices doing their own thing: AX3000T pipe dial-up and 5G, and the AC2100 pipe 2.4G device that is slow, and it works fine all year round.
