Wi-Fi shares the air with everyone nearby. Speed therefore comes less from your hardware than from how much room you have and who you share it with. The fields for channel, width and power sit at the bottom of the Wi-Fi section, in advanced. The wizard deliberately leaves them on automatic, because for most networks automatic is the right answer.
The bands
- 2.4 GHz reaches far and goes through walls, but it is crowded and in practice has only three channels that do not overlap. Use it for range and for older equipment, not for speed.
- 5 GHz has many more channels and is almost always where your real throughput comes from. Walls cost more signal here than at 2.4 GHz.
- 6 GHz is empty and fast, but has the shortest range and only works with clients that support it. Only the newest models have such a radio.
Channel width
You set the width per band, not per SSID: every SSID on the same radio shares the same channel.
- 2.4 GHz: 20 MHz or 20/40 MHz. The default is 20 MHz, and in any street or office building that is also the right choice. A 40 MHz channel at 2.4 GHz takes up nearly half the band and mostly buys you a fight with the neighbours.
- 5 GHz: from 20 MHz up to 20/40/80/160 MHz, and 20/40/80/160/320 MHz for Wi-Fi 7. The default is 20/40/80 MHz.
Wider is only faster when the channel is genuinely free. A wide channel steps up to its full width only when nothing else is in it, and it falls silent sooner once something is. It also reaches less far at the same power, because that power is spread over more spectrum. And the wider your channels, the fewer fit side by side: at 80 MHz you are left with a handful of non-overlapping channels in Europe, at 160 MHz fewer still. With several access points, pick 40 or 80 MHz on purpose.
The 5 GHz width field applies to every radio that is not 2.4 GHz, so on a device with both a 5 GHz and a 6 GHz radio the two get the same width. The same is true of the frequency field. If you need them to differ, set that by hand on the device afterwards.
Fixing a frequency
The two frequency fields take a number in MHz, not a channel number. Empty means automatic, which lets the device look for a channel itself.
- 2.4 GHz: channels 1, 6 and 11 are
2412,2437and2462. Anything else overlaps with those three and makes it worse for everyone. - 5 GHz indoors in Europe: 5180 to 5320 (DFS from 5260) and 5500 to 5700, that last block entirely DFS.
Fix a frequency only when you have a reason, for example because you want to keep several access points apart yourself. Fixing it also means the device will no longer move away when interference turns up.
Country and the legal limits
The Country field is not cosmetic. It decides which channels the device may use, how much power it may transmit and where it has to check for radar. The configurator writes the country into the configuration, and on the old wireless package also frequency-mode=regulatory-domain, so RouterOS keeps to those limits. Set it to the country the device is actually in. In a site with several devices the country is set once for the whole site and carried to every device.
EIRP and transmit power
The legal limit is not about the power of the radio but about EIRP: what the radio transmits plus what the antenna adds to it. Indoors in Europe that comes down to 20 dBm at 2.4 GHz and 23 dBm at 5 and 6 GHz. Those are also the figures the Wi-Fi plan starts from, adjustable per band per access point.
The TX power field sets the power in dBm below that maximum. Empty means as much as the country allows. You cannot get more out of it than the limit, so the field is there to go down, not up.
Turning it down helps more often than it sounds: an access point that shouts too loudly is still heard in places where the phone itself can no longer be heard back, and clients then stick to it instead of moving on. See Recipe: Wi-Fi that keeps working as you walk.
The TX power field is only written into the script for devices on the new wifi package. If your device runs the old wireless package, power stays at whatever the regulatory domain allows and you set it by hand on the device if you need to.
Antennas in the plan
Most access points radiate all around. A few models look one way, a wall-mounted unit for instance. In the Wi-Fi plan you pick omnidirectional or a sector per access point, with a beam width and a direction, and see what that costs behind the device. Models known to be directional get that setting automatically; the catalogue holds no other antenna data, so everything else starts out omnidirectional.
Spreading channels over several access points
- At 2.4 GHz: only 1, 6 and 11, 20 MHz wide, and never the same channel on neighbouring access points.
- At 5 GHz: give every access point its own channel. Prefer 40 or 80 MHz so you have enough channels left to really keep them apart.
- Access points that cannot hear each other may share a channel; the plan shows which ones overlap. If they do hear each other they wait for each other, and you get half the throughput at best.
DFS
Part of the 5 GHz band is shared with radar. There the device has to listen before it transmits, and keep listening while it does. If it hears radar it must leave the channel immediately, and your Wi-Fi drops out for a moment. The wait before use is one minute on some channels and ten minutes on others.
For devices on the wifi package the configurator sets up the 5 GHz channel so that the channels needing the ten-minute check are skipped. That saves you an access point that is silent for ten minutes after every reboot. If there is a weather radar or an airport nearby, DFS channels are a bad idea anyway: pick a frequency below 5260 by hand.
What you can check
On the device itself, /interface wifi print or /interface wireless print shows which frequency and width the radio actually ended up on, because automatic only chooses at startup. /interface wifi registration-table print shows how strongly each client is coming in.
Next
The settings themselves are in Setting up Wi-Fi, coverage is drawn in The Wi-Fi plan, and for several access points under one manager see CAPsMAN.