The picture is nearly always the same. A laptop or a phone is gone for a moment, the connection comes back by itself, and a PC on a cable notices nothing. Sometimes it lands in the middle of a video call, sometimes it happens at night and you only find it in the log.
Start with what it is not. If the wired side drops as well, this is not a Wi-Fi problem: look at your uplink, your bridge or the router itself. If one device hangs while the rest carries on, the device is the likeliest suspect. Wi-Fi dropping means several wireless clients, repeatedly, with the cable untouched.
The quick checks, in order
- Are they really dropping, or moving? Look at who is connected and for how long. On the new package:
/interface wifi registration-table print, on the old one:/interface wireless registration-table print. A good answer shows uptimes in hours. Uptimes in seconds or minutes across the board mean clients are reconnecting over and over. - What does the log say?
/log print where topics~"wifi"for the wifi package,/log print where topics~"wireless"for the legacy one. You are after the reason behind the disconnect. "extensive data loss" or "connection lost" points at the radio. A repeated "group key timeout" or a 4-way handshake timeout points at the security settings. - How strong is the signal? The same registration table shows the signal per client. Anything above -65 dBm is comfortable, -65 to -75 dBm works but is fragile, below -75 dBm it starts falling over. This is the most common cause and also the dullest.
- How busy is the channel? Scan with
/interface wifi scan wifi1 duration=5, or on the legacy package/interface wireless scan wlan1. Ten neighbours on the same channel explain a lot. Note that scanning takes the radio off the air, so do not do it during a meeting. - Is the router itself calm?
/system resource print. A CPU pinned near 100 percent makes Wi-Fi stutter too. If that is what you see, carry on at CPU at 100 percent.
The usual causes, most common first
Not enough signal where it goes wrong
An access point covers less than you think, certainly through a concrete floor or a cavity wall with foil insulation. The client holds on until it really cannot and then lets go. The fix is an access point closer by, not more transmit power: the client transmits weaker than the router does, so shouting louder only helps in one direction.
A busy channel, or one that is too wide
On 2.4 GHz there are three channels that do not overlap: 1, 6 and 11. Set the width to 20/40 MHz and you take two of them at once, which guarantees a collision with the neighbours. Put 2.4 GHz on 20 MHz. On 5 GHz, 80 MHz is usually fine, but in a block of flats 40 MHz gives a steadier connection.
DFS: the radio has to leave the channel
The 5 GHz channels from 5260 MHz upwards are DFS channels. If the radio sees something that looks like radar it has to vacate within seconds and wait around ten minutes. Every client loses the connection at the same moment. Near an airport, a harbour or a weather station this is very likely your cause. Fix the frequency at 5180, 5200, 5220 or 5240 MHz and it goes away.
Power and heat
An access point on PoE at the end of a long, thin cable gets too little voltage and reboots under load. Check the uptime in /system resource print: a few minutes, every time you look, means it is restarting. Heat does the same, especially in a closed cabinet.
Power saving in the client
Windows laptops and phones switch their radio off to save battery. From the router's side that looks exactly like dropping. If it is one brand of laptop or one phone, the router is innocent.
What the configurator does about it
The tool sets channels and widths, but it measures nothing: it has no idea what your neighbours are doing. What it does do:
- Channel width 2.4 GHz defaults to 20 MHz, with the reason in the option itself. That is the single setting that most often fixes this.
- Frequency 5 GHz and Frequency 2.4 GHz are empty by default, which means automatic. The help text names the DFS boundary: 5180-5320 with DFS from 5260. Filling in a fixed frequency below 5260 avoids DFS entirely.
- Country decides which channels and what power are allowed. Set it wrong and the radio can end up on a channel your clients are not allowed to listen on.
- In a site with several devices, the site check reports that not every access point broadcasts the same SSIDs. That is not dropping, but it looks like it from the sofa.
There is deliberately no automatic channel selection and no site survey in the tool. A scan belongs on the hardware itself, with the radios that are actually there.
The honest limits
You cannot configure your way out of the neighbours. A flat with thirty networks in the air stays a flat with thirty networks in the air, and the only things that really help are 5 or 6 GHz, a narrower channel and an access point closer to the people. A client that decides to let go, lets go: 802.11r, k and v make switching faster, they do not hold anyone in place. And an access point fed by a repeater instead of a cable shares its radio time with the uplink, which doubles every problem on this page.
Read on: Channels and width, Measuring Wi-Fi and Wi-Fi is slow.