Should I buy two or three Mesh? 89 sqm three-bedroom test, but the third unit I forced to add actually cut the speed test in half
Last month,
helped my cousin install whole-house WiFi. The e-commerce page defaulted to three units, which cost about 200 yuan more than two. The page said "big apartments for one-step service," so he figured the price difference wasn't big anyway, so he paid. Their 89-square-meter three-bedroom unit, with two fully installed units, the signal never dropped below -64. The third unit felt awkward wherever I put it. I couldn't give up and tested it in the study all night, and the speed test actually dropped from 280 Mbps to 130 Mbps. This machine is still gathering dust in a drawer to this day.
this matter helped me break down the "actual number of Mesh units to buy." Here's the conclusion: the number of units depends on both the partitioned layout and the return route, and it has little to do with whether your budget is sufficient. The extra one not only wastes money, but if placed wrong, it actually makes things worse.
first calculate the coverage account: how big does one node manage
The common rule in
circle is allocate one node every 60 to 80 square meters. Note that this is the "effective area," not the building area; your shared area and entryway are not included. More important than area is the partition: between nodes, it's best to have only one load-bearing wall, and no more than two. The steel-concrete structure of the load-bearing wall consumes 15 to 25 dB at once. After two blocks, even the strongest signal leaves very little. This was verified by me when I used my phone to test blind spots all over the house. The method is included in the WiFi Signal Blind Spot Self-Check article.
so, for the same 89 sqm, the open layout and the gun layout are two different answers. My cousin's living room is central, with a hallway connecting three bedrooms. The second unit in the hallway can accommodate the master bedroom, study, and kitchen at the same time—two units are enough. If your home is L-shaped or narrow, with one router covering one end but not the other, that's a three-unit setup.
five common apartment types directly corresponding:
| apartment type | recommended number of units | note in one sentence |
| one-bedroom/studio (within 60 sqm) | 1 units | the main router can be placed in the middle to cover everything, no need to Mesh |
| 2 two-bedroom (60-90 sqm) units | the second unit to compensate for the furthest bedroom | |
| three-bedroom (90-140 sqm) starting | 2 units | only consider the third unit when the corner is below -75°C |
| Duplex/duplex (150㎡+) | at least one unit per floor | floor slab attenuation is more severe than walls; one unit must be independent upstairs |
| one unit per floor for multi-story self-built houses | Use vertical shaft network cables for wired backhaul, don't rely on wireless threading through floor slabs |
duplexes and self-built property lists: cast-in-place slabs about ten centimeters thick plus reinforcement mesh have worse attenuation than 24-brick walls. Relying on wireless backhaul penetration from upstairs and downstairs is basically superstition. My cousin's three-story self-built house has a weak current box network outlet on each floor, with a single node on each floor running a pure wired backhaul. That planning concept is detailed in the rural self-built house network planning , with signal on each floor on three floors below -50.
my 89 square meters: Here are the actual test data for two units
just talking about rules is useless, just upload the data. The main router AX3000T placed in the living room TV cabinet, which is the central area of the whole house's network. Choosing the right location is a pitfall. I once wrote an article where the router best signal, and the core rule is: don't put a weak current box in. When only the main router is enabled, the signal at six points throughout the house:
| only install the main router | corridor, and the second station after the | |
| Living Room Sofa | -45 | -44 |
| Dining Room | -52 | -52 |
| Corridor | -63 | -52 (node body) |
| Master bedside | -71 | -58 |
| Study desk | -78 | -64 |
| Kitchen | -69 | -61 |
second unit isn't just left out casually. The sub-router should be placed "at the edge of the main router signal, halfway in the target area." Placing it next to the main router is like buying for nothing, and placing it in a blind spot can't connect to the main router. I tested eight points with my phone before setting it above the corridor shoe cabinet. This measurement method is included in the Mesh article on sub-router placement .
Final results for
two units: Worst study in the house - 64, actual test download speed around 280MB. 4K live streaming has a bitrate of up to 25MB, and 280MB is ten times redundant—this is the confidence behind the 'two channels are done.' What does -64 mean? You can compare it to signal segmentation: use anywhere within -50, use it normally between -60 and -70, and only after -75 do you need to figure out a solution.
the third car I forcibly added, why does the speed test drop instead of increase
third unit is in the study, with the phone sticking to it with a full signal of -48. By rights, shouldn't it be taking off? The speed test was 130 Mbps, which was more than half the 280 Mbps of the direct corridor unit. My cousin's first reaction was that the machine was broken, but the principle was obvious.
in wireless backhaul Mesh, data transmission between sub-routers and master routers also relies on WiFi. Data travels from the phone to the third unit in the study, then from the third wireless device to the second channel in the corridor, and finally from the second device to the main router. This is two-level wireless cascading . For single-frequency backhaul machines, backhaul data competes with mobile internet data in the same frequency band, with each cascading speed nearly halved: the main router started at just over 940 Mbps, the one in the corridor dropped to 280 Mbps, and the third in the study dropped to just 130 Mbps. When I used the Mercury router for wireless bridging tests, the same pattern applies: after bridging, the speed was cut in half. The wireless bridging setup contains complete data.
the third device's full bars are a lie; the number shows the connection quality from the phone to the third device, and the speed lag shows the of the path from the third device back to the back. This is also why, according to Huawei's official standards, Mesh cascading is not recommended to exceed level 3—the deeper the cascade, the worse the end speed.
is not without solutions. When the study was renovated, I left a network port, so I switched the third unit to a wired backhaul network cable, and the speed immediately returned to 460Mbps. But looking back, the study directly connected to the corridor already had 280MB available, so the extra 180MB is just a nice number—watching videos or gaming feels completely different. The article covers how to connect wired backhaul and the pitfalls of optical modems and switches, how to connect wired backhaul is thoroughly explained.
under what circumstances is buying a third car really worth it
isn't a one-shot killing for three items; it really works in three situations:
First, the corner position is below -75, and no matter how much the second car moves, it can't be revived. Note that the premise is to first measure the points in the positioning article. Many people's "poor signal" is actually because the sub-router was placed in the wrong position; a simple shift solves the problem without spending on a third unit.
Second, there is no network cable on duplex buildings. The upstairs unit has an independent main router directly connected to the downstairs building, cascading only one level, allowing for controllable speed loss. This is the standard solution for the multiplex.
third, room has a network port and can connect wired return . The third network cable becomes an AP with mesh roaming, with no loss. It counts in places like the master bedroom or study where there are renovated ports. That's why I always say that wiring during renovation is worth more than anything. If you don't have wiring, regret is to patch up the whole house with network cables.
also mention the tri-band Mesh: it adds an independent 5G band specifically for backhaul, so it doesn't compete with phones for bandwidth, reducing cascading loss. But for the same tier, three-frequency is about 1,000 yuan cheaper than dual-band. In an 89-square-meter apartment, two dual-frequency units have redundancy. The three-band is reserved for duplexes in large apartments, while in smaller apartments, getting triple-frequency is just a way to pay for a listen.
do two things before placing an order: save one car if you can
the first item, test it before buying . Holding your phone, you can walk around the signal points throughout the house and memorize them. The method takes five minutes and costs zero. If the worst point in the whole house is below -70, it means you don't use Mesh at all. Moving the main router or changing the channel might solve the problem. If the bedroom is short of breath, first dig up the old router at home, switch to wireless relay or AP mode to fill a single room. It's a zero-cost solution. You can do this in the of changing the old router to relay. The downside is that it breaks briefly while moving to a room, which is more than enough for those who don't mind roaming.
second item, think carefully about whether you want seamless roaming . Mesh's core selling point is just one thing: walking around the room with your phone and videos streaming without interruption. The relay plan couldn't do this, so it was Mesh's turn to step in. How to choose a solution, which is better compared to AC+AP, and how to choose between AC+AP and Mesh I've written a complete comparison. I really bought two devices, followed the networking process the Xiaomi Mesh networking article, and it was done in half an hour.
one thing to note when purchasing: many brands allow separate repurchase periods. If you find two units of the same model after two months and find the corners are insufficient, you can just buy a unit of the same model and add them together. You don't have to pay the price difference for the three units from the start. My cousin's third unit that gathered dust was eventually bought by me at half price and put in my mother-in-law's living room, so it was basically a good use of it.
the order at the end, following it basically won't go wrong:
| steps | actions | cost |
| 1 | check the signal at all the house locations, confirm the worst value is | 0 yuan |
| 2 | move the main route location + change the channel | 0 yuan |
| 3 | old routes converted to relays or AP blind spot patches | 0 yuan |
| 4 | two Mesh units, measuring the pendulum routing by point | for about 300 yuan |
| 5 | the edges still below -75, so I bought one unit separately. With Ethernet ports, priority wired return | about 150 yuan |
