Open any Wi-Fi analyzer and you get five fields: a name, an address, a band, a channel and a signal level. Most people read the last one and ignore the rest, which is a shame, because the signal level is the field that explains the least.
Here is what each one is, and what it lets you decide.
SSID: the name, and what it does not guarantee
The SSID is the network name, up to 32 bytes of whatever the owner typed.
That is all it is. It is not unique and not an identity. Nothing stops a
second router in the building from also calling itself Home, and nothing stops
a deliberately hostile one from copying yours exactly. Your phone picks by name
and signal, so "it connected automatically, so it must be my network" does not
follow.
Hiding the SSID is not the security control it is sold as, either. The name still travels in the frames your own devices send when they look for it, so it is recoverable by anyone who cares. What hiding actually achieves is breaking discovery on some clients and making your devices announce the network name wherever you carry them. Use a password, not a secret name.
The useful thing about an SSID is that several access points can share one. That is how roaming works: your phone moves from the router in the living room to the one in the bedroom without you retyping anything, because both advertise the same name. Which raises the obvious question - if the name is shared, what identifies the radio you are actually talking to?
BSSID: the address that identifies one radio
The BSSID is the MAC address of the specific radio serving you. Six bytes, shown
as a4:2b:b0:1f:3c:d8.
One SSID, many BSSIDs is the normal case, not the exception:
- A dual-band router has a different BSSID on 2.4 GHz and on 5 GHz, even though
both say
Home. - Every node in a mesh has its own.
- Every extra SSID on the same radio gets its own, usually incrementing by one.
This is the field that turns "the Wi-Fi is bad" into a specific answer. Note the BSSID at your desk, walk to the room where calls drop, and look again. If it changed, you roamed and the gap you felt was the handover. If it did not change and the signal has fallen to -80 dBm, your phone is clinging to a distant access point while a much closer one sits idle - a sticky client, which is a different problem with a different fix.
The first three bytes are the OUI, the vendor block, so a BSSID usually tells you who made the radio. Note the limit here: that is the AP you are associated with. Android deliberately blocks apps from reading the MAC addresses of other devices on the LAN, so vendor identification for everything else on the network is inference, not fact.
Bands: 2.4, 5 and 6 GHz
One trade-off drives all three. Lower frequencies travel further and pass through walls better; higher frequencies carry more data and have more room.
| Reach | Spectrum | Real-world use | |
|---|---|---|---|
| 2.4 GHz | Best | 3 usable channels | Far rooms, IoT, crowded everywhere |
| 5 GHz | Medium | ~25 channels, many DFS | The default for anything that matters |
| 6 GHz | Shortest | Widest, cleanest | Wi-Fi 6E/7 devices in the same room |
2.4 GHz is not just crowded with Wi-Fi. Microwave ovens, Bluetooth, wireless mice, baby monitors and cheap cameras all sit in the same band. It reaches the back bedroom, and that is the only argument for it.
6 GHz needs Wi-Fi 6E or Wi-Fi 7 at both ends. A Wi-Fi 7 router does nothing for a phone that has no 6 GHz radio, and availability still depends on your country's regulator.
Channels: why everyone says 1, 6 and 11
On 2.4 GHz, channel numbers are spaced 5 MHz apart, but a transmission occupies about 20 MHz. The arithmetic is unforgiving: each channel spills across roughly four neighbours on each side.
Work it through and only 1, 6 and 11 fit side by side without overlapping. Channels 12 and 13 exist in Europe and much of Asia but not North America; channel 14 is Japan-only and 802.11b-only, so treat it as a museum piece.
Now the counterintuitive part, and the reason "I picked channel 3 to avoid everyone" is worse than useless:
Partial overlap is worse than sharing a channel. Two access points on the same channel can hear each other, so they take turns - you lose airtime, but the protocol is working as designed. Two access points on channels 3 and 6 cannot decode each other. Each just registers the other as raw noise it has to shout over. Sharing channel 6 with your neighbour beats sitting between them.
5 GHz has far more channels, but roughly half of them are DFS channels shared with radar. An access point must listen for 60 seconds before it may use one, and if it detects radar it must leave within 10 seconds and stay off that channel for 30 minutes. That is why a 5 GHz network sometimes vanishes for a while near an airport or a weather station. DFS channels are usually emptier and usually worth it; just know why the outage happened.
6 GHz has so many channels that scanning them all would take over ten seconds, so the standard defines 15 Preferred Scanning Channels spaced 80 MHz apart - 5, 21, 37, and so on up to 229. Access points beacon on those, and clients only scan those. If a 6 GHz network is invisible, a non-PSC misconfiguration is a good first guess.
Channel width: wider is not better
20, 40, 80, 160 and, on 6 GHz with Wi-Fi 7, 320 MHz.
Doubling the width roughly doubles throughput in clean air. In air that is not clean, a wider channel collects proportionally more interference, spreads the same transmit power across more spectrum, and consumes the space that would have let you avoid your neighbours.
The practical rules:
- 2.4 GHz: always 20 MHz. A 40 MHz channel eats most of the band and guarantees a collision with someone.
- 5 GHz in an apartment block: 40 or 80 MHz. 160 MHz sounds better and usually is not, because there is almost nowhere clean to put it.
- 6 GHz: go wide. This is the band that has the room.
In a dense building, narrow and clean beats wide and contested. Every time.
dBm: the number behind the bars
Signal strength is measured in dBm - decibels relative to one milliwatt. It is negative because the power arriving at your phone is a tiny fraction of a milliwatt, and the scale is logarithmic:
- 3 dB is half. -63 dBm is half the power of -60 dBm.
- 10 dB is a factor of ten. -70 dBm is one tenth the power of -60 dBm.
So the gap between -60 and -70 is not "slightly worse". It is an order of magnitude, and it is the difference between a wall in the way and no wall.
| Reading | What it means |
|---|---|
| -30 dBm | Practically touching the router |
| -50 dBm | Excellent |
| -67 dBm | The design target for voice and video |
| -70 dBm | Floor for reliable web and email |
| -80 dBm | Unreliable, expect drops |
| -90 dBm | Nothing usable |
If you remember one number, remember -67 dBm. That is the level networks are designed to deliver everywhere they are meant to work, and it is the threshold to measure against when you are deciding where an access point should go.
The bars on your phone are a vendor's arbitrary mapping of this number. Four bars on one handset is three on another. The dBm figure is the thing that can be compared.
The number dBm does not give you
Here is the reading that explains "full bars, still unusable", which is otherwise baffling.
dBm tells you how loud your access point is. It says nothing about how loud everything else is. That second number is the noise floor, and the difference between them is the signal-to-noise ratio:
SNR = signal - noise
In a quiet house the noise floor sits around -95 dBm. A -70 dBm signal there gives you 25 dB of SNR, which is comfortable. Put the same -70 dBm signal in an apartment block where forty neighbouring radios have pushed the noise floor to -80 dBm, and you have 10 dB. Same bars. Unusable connection.
| SNR | Result |
|---|---|
| 30 dB and up | Everything works, including 4K and large transfers |
| 25 to 29 dB | Comfortable for calls and HD video |
| 20 to 24 dB | Inconsistent, users start complaining |
| Below 20 dB | Drops and stalls |
The important consequence: when the problem is noise, a stronger signal does not fix it. Moving the router closer raises signal and noise together. The fix is to move to quieter spectrum - a different channel, or a different band entirely. That is a decision you make by looking, not by guessing.
Putting it together
A Wi-Fi problem is usually one of three things, and the five fields tell you which:
- Too far - dBm worse than -70, SNR fine. Move the AP, add a node, or drop to 2.4 GHz for reach.
- Too noisy - dBm fine, SNR under 20. Change channel or band. Narrow the channel width.
- Wrong radio - dBm poor but a closer AP exists, BSSID not changing. A sticky client, or an AP whose power is set too high.
The procedure for picking a channel is the same in every case, and it takes two minutes:
- Look at what is actually on air around you, per band, with signal levels.
- On 2.4 GHz, choose whichever of 1, 6 or 11 is least occupied. Never anything between them.
- On 5 GHz, prefer a channel nobody near you is using, DFS included.
- Set the width as narrow as your throughput needs allow, not as wide as the router offers.
- Re-measure at the far end of the space, not next to the router.
"Auto" on a consumer router picks once, often badly, and then keeps that choice for years. Two minutes with real readings beats it almost always.
Where to read these numbers
Everything above is visible from a phone, if the app shows the raw values rather than a smiley face. That was the reason we built one.
NetTools: Network Analyzer shows live dBm updated about once a second, a channel chart for 2.4, 5 and 6 GHz so you can see which channels your neighbours are on before you pick, and BSSID, band, channel width and link speed for the network you are on. Nearby-network scanning is rate-limited by Android itself, so it shows a real cooldown timer instead of pretending to refresh continuously.
And if the question turns out to be the internet connection rather than the Wi-Fi link, measuring that properly is a different job with different tools.
