Can a robot vacuum still sweep if the internet is disconnected? I turned off WiFi for three days, didn't lose the map, only four things were missing

started last month when I checked the router's backend traffic statistics, and the robot vacuum managed over 80MB of upstream and downstream traffic in a month. A machine spinning on the ground—why would it upload so much material? I checked around casually, and the more I checked, the more annoyed it became. So I decided to do an experiment: disconnect its external network, but the WiFi was still connected, but it still wasn't allowed to go out. After three days, the conclusion was quite interesting—it didn't care at all.

to get straight to the point: sweeping is a local job, and even if the internet goes down, it still gets to work

many people have a default impression: smart devices are just bricks when the internet goes off. A speaker with a disconnected network is indeed more than half useless; a camera goes offline and goes blind, but robot vacuums are an exception. cleaning is done entirely by machines themselves, with algorithms running on onboard chips and no cloud .

its laser head scans the terrain by itself, maps itself, plans routes by itself, and then finds the charging dock after scanning. In this whole sequence, there's no step to send data to the server and wait for a reply—which makes sense. If the internet goes down, you just lie down, and if the internet shakes halfway through cleaning, whose responsibility is the machine stuck in the living room? Manufacturers wouldn't dare design it this way.

my Mijia vacuum mop, it had to crash five times before it connected. I once wrote an article about failed network setup for robot vacuums. This experiment essentially reverses verification: whether it connects and whether it can scan are two different things.

three-day test: timed and never late, avoided the restricted area, and didn't lose the map

On the first day

the external network was cut off, at 9 a.m., it came out of the charging dock and started work on time, just like usual. I only later learned the reason: scheduled tasks are machine-native and do not rely on the cloud to send . This is similar to the temperament my smart socket home—it still executes on time when the network is off, much better than some electric curtains that set timers to the cloud—but when the router restarted, the curtain was opened at 7 a.m. and didn't do it at all. I had to compare the two designs to understand.

I deliberately observed the penalty area. I have two places at home: one around the cat food tray and one around the bathroom floor drain. When the internet is offline, it wraps itself cleanly and doesn't break through even once. map and restricted zone data are stored in the local storage chip, so when cleaning, you read the local data directly without looking back to the cloud. So you can let go of the worry about "losing the map if the internet goes off"—for a normal used machine, losing maps is usually due to moving, resetting the machine, or sensor malfunction, not the internet disconnection.

for three days, it timed once a day, and I manually started it once with the body's buttons. After scanning, it automatically recharged, and the whole process didn't drop the link.

only lose four items, and you might not actually use two of them

three days offline, the real losses are as follows:

fourth point needs to be mentioned separately. The voice transmission is the speaker understands your speech, sends commands to the cloud, and then forwards them to the vacuum cleaner. Once the outer network is cut off, the middle section is cut off. The speaker's local wake-up and response are still alive, but it can only reply with one message: "Network service is not reachable"—exactly the same symptom I had when I tested the speaker's network disconnection before. How much capability is left after a voice assistant goes offline? I wrote about in the article on how to choose a smart speaker.

On the fourth day

, I put my external access back and opened the app. The map was still there, but the cleaning record was missing three from the three days of disconnection. This means local scanning is a to save up and synchronize with the internet. This serves as a reminder for those who want peace of mind: if you use the internet for a long time, the app history clearance is basically an empty ledger.

Why did I decide to cut off the external internet for it

Back to those eighty-plus MB. The data uploaded by the robot vacuum includes usage logs, cleaning statistics, and maps. the laser map you built is your home's floor plan which room is where, how furniture is arranged, which wall the door is on, all on it. Add in the cleaning time, and the pattern of when someone is home and when no one is there—the pattern is complete.

earlier lesson was at the end of 2022, when MIT tech reviews exposed that iRobot's Roomba J7 test unit had cameras and photos taken at home sent to outsourcing companies for data annotation. The annotators posted the photos on foreign social media platforms and groups, showing people sitting on toilets. Test users signed consent forms, but unaware elderly and children at home did not. After this, iRobot narrowed down the outsourcing process, but it shows one thing: machines with cameras transmit images to the cloud, every link in this chain is a risk .

My car uses LiDAR, without cameras, so the risk is much lower. But ever since I checked the privacy settings of all six cameras in my home, I've become suspicious about 'what devices at home transfer to the cloud.' My experience with that camera inspection is included in home camera security self-inspection , and the vacuum cleaner is an extension of the same type of issue.

figured it out: it's not about cutting off WiFi, it's about cutting off the external internet

I really wanted to disconnect my WiFi, I couldn't bear to do it—after all, area cleaning and remote start are still nice once in a while. So the compromise is: keep the local area network and cut off the from the outer network.

specific steps, I found the vacuum cleaner device in the device management section of the main router backend and turned off its internet access. Most brands have similar switches in their backends. Mercury says 'No Internet,' and Tenda has a corresponding button in device management—just flip it and you'll find it. After turning it off, it remains connected in the WiFi list, and sometimes it can work within the same local area network as the app, but you just can't leave the house.

don't want to touch the router, there's a more thorough idea: my home already has a dedicated 2.4G IoT network, feeding those smart little devices costing just a few dozen yuan. The vacuum cleaner is also attached to this network, separated from the main network. I usually manage this network quite strictly. I've written about how to convert old routers to AP private networks Xiaomi routers are split into IoT private networks. For those with dozens of devices at home, it's worth getting involved. I've counted the ledger for my more than forty devices in the article on how to handle smart home devices .

Also, don't overlook those inconspicuous switches in the app. Looking through settings, phrases like "User Experience Improvement Plan" and "Data Sharing" basically send data to the cloud, so you can turn them off one by one. If you don't need Map Cloud backup, turn it off too—just leave the map on your own device.

Who can't live without the internet, and who just doesn't connect at all

After

three days of trying, I have a much clearer understanding of this thing. The kind you buy for elderly family members, or if you're a button enthusiast yourself, you don't have to WiFi at all: set a timer on the machine (the old model already has buttons), set the restricted area once, and take care of the rest itself, without the privacy concern. I skipped the network setup hurdle, and I didn't have to go through the slot of five blowdowns back then.

conversely, the following three types of people still honestly stay online:

• office workers want to start remotely on their way home and get home clean—this is something offline users can't replace;
• a large house of over 100 square meters, I was used to dividing rooms into zones and scanning wherever I pointed out;
• pet sheds a lot at home, you need to clean multiple rounds a week and check the progress in real time.

for the rest, I suggest everyone try cutting off the external internet like I did. The method is simple: turn off one device's permissions in the router's backend, run it for two days, and see if you need those four features. If not lacking, it will always be broken; If it's missing, you can put it back anytime, with no side effects at all. When it comes to smart devices, before connecting to the internet, you should first clarify "how many functions are left after disconnection." I've used this ruler repeatedly in articles about toilet seats and electric curtains, but this time it was about the robot vacuum, which made it clear: it's one of the few smart devices at home that can be disconnected without interrupting your main tasks.