If you’re an IT director at a school or small business, you’ve likely encountered terms like “dB,” “signal strength,” or “RSSI” when managing your Wi-Fi network. Whether you’re using Fortinet’s FortiAPs, Cisco Meraki’s MR series, HP Aruba’s access points, Ruckus AP’s, or Ubiquiti UniFi’s APs, these metrics pop up in your management console—and they can feel like a foreign language. At Twotrees Technologies, we’re here to demystify Wi-Fi signal measurements so you can keep your network running smoothly for students, staff, or employees. Let’s dive into what these numbers mean, how to spot a good signal versus a bad one, and what’s “acceptable” for your environment.
What Are Wi-Fi Signals, and How Are They Measured?
Wi-Fi signals are all about power—how much of the signal your access point (AP) sends out actually reaches a device like a laptop or phone. This power is measured in dBm (decibels relative to one milliwatt), a scale that might look confusing at first because it uses negative numbers. Here’s the gist:
- 0 dBm equals 1 milliwatt of power, but Wi-Fi signals are tiny, so you’ll see values like -30 dBm or -70 dBm.
- Closer to 0 is better: A signal at -30 dBm is stronger than one at -70 dBm.
- It’s logarithmic: A small change in dBm (like 3 dB) halves or doubles the power, so -60 dBm is way weaker than -50 dBm.
Think of it like a flashlight: the farther you are from the light, the dimmer it gets. Walls, distance, and interference (like other networks) dim your Wi-Fi signal too, and that’s what your management dashboard is showing you.
Decoding Signal Strength in Your Wi-Fi Console
When you log into your Wi-Fi system—whether it’s Fortinet’s FortiGate interface, Cisco Meraki’s cloud dashboard, HP Aruba’s Central, Ruckus One, or Ubiquiti UniFi’s Network app—you’ll see signal strength for connected devices. It might be labeled “Signal,” “RSSI,” or even a percentage. Here’s what it’s telling you:
- Signal Loss: The difference between what your AP sends out (e.g., 20 dBm) and what the device receives (e.g., -50 dBm) is the “loss”—in this case, 70 dB. Loss happens because of distance, walls, or noisy airwaves.
- Your Goal: Keep the received signal strong enough for reliable connections.
What’s a Good Signal? What’s a Bad One?
Let’s break it down with examples you might see across vendors:
- Excellent Signal (-30 to -50 dBm):
- What it feels like: Lightning-fast Wi-Fi—perfect for streaming lessons in a classroom or video calls in a meeting room.
- Example: A teacher’s laptop right next to a Ubiquiti UniFi AP in the same room might show -40 dBm. In Cisco Meraki, you’d see a full signal bar.
- Real-world: Devices close to the AP with no obstacles.
- Good to Fair Signal (-50 to -70 dBm):
- What it feels like: Fine for browsing, email, or watching standard videos. At -70 dBm, you might notice slight slowdowns.
- Example: A student’s tablet one room away from an HP Aruba AP might hit -60 dBm in Aruba Central. Fortinet’s FortiAP might show “75% signal.”
- Real-world: One drywall or a short hallway between the device and AP.
- Poor Signal (-70 to -90 dBm):
- What it feels like: Pages load slowly, videos buffer, and connections might drop. At -90 dBm, it’s barely usable.
- Example: A staff phone two floors below a Cisco Meraki MR AP might register -80 dBm in the Meraki dashboard. Ubiquiti UniFi might show “10% signal.”
- Real-world: Multiple walls, floors, or heavy interference.
- Unusable Signal (Below -90 dBm):
- What it feels like: Devices can’t connect reliably—or at all.
- Example: A guest device outside, far from a Fortinet FortiAP, might drop off entirely in FortiGate’s logs.
What’s “Acceptable” Signal Loss?
“Acceptable” depends on what your network needs to do. For a school streaming educational videos or a business running cloud apps, aim for a received signal of -67 dBm or better. Here’s why:
- Most APs (like Fortinet’s FortiAPs or Ubiquiti UniFi APs) transmit at 20-23 dBm.
- A loss of 50-70 dB (arriving at -50 to -70 dBm) is typical and works well for most uses.
- Over 70 dB loss? You’ll start seeing complaints about slow Wi-Fi.
For example:
- A classroom iPad showing -65 dBm in Ruckus One console (after 85 dB loss from a 20 dBm AP) is fine for daily tasks.
- A library laptop at -75 dBm in Cisco Meraki (95 dB loss) might struggle with Zoom calls.
How to Use This in Your Wi-Fi System
Next time you’re in your dashboard:
- Check Clients: Look at connected devices. In Ubiquiti UniFi, it’s under “Clients” > device details. Fortinet shows it in “Wireless Clients,” Meraki in “Wireless > Access Points,” and Aruba in “Clients.”
- Spot Weak Signals: If you see -70 dBm or lower, that device might need help.
- Fix It: Move APs higher or closer, tweak power settings (e.g., “High” in UniFi or “Auto” in Meraki), or add more APs if losses exceed 70-80 dB in key areas.
Common Wi-Fi Q&As for Schools and Businesses
Managing Wi-Fi can spark plenty of questions, especially when you’re keeping a school or business connected without a deep dive into networking. Here are some common queries we get from IT directors, answered simply to help you optimize your Fortinet, Cisco Meraki, HP Aruba, Ruckus, or Ubiquiti UniFi network.
Q: Why don’t I just turn each AP on full power to get a stronger signal everywhere?
A: Cranking your access points (APs) to max power—like 23 dBm on a Ruckus R series or Ubiquiti UniFi AP—seems like an easy fix for weak spots, but it can backfire. High power makes APs “shout” over each other, causing interference, much like overlapping voices in a noisy cafeteria. This can drop signal strength (e.g., from -50 dBm to -70 dBm) and slow things down. Plus, distant devices might hear the AP but lack the juice to reply. Instead, use “Auto” power settings (like in Cisco Meraki or HP Aruba) or medium levels (e.g., 15-20 dBm in Fortinet or Ruckus One) and position APs to cover without clashing.
Q: My console shows -80 dBm for some devices. Is that bad? What should I do?
A: Yes, -80 dBm is weak—think “poor signal” territory. Devices at this level might crawl online, drop calls, or disconnect. You’ll spot this in dashboards like Ruckus One’s “Clients” tab, Fortinet’s “Wireless Clients,” or Ubiquiti UniFi’s device details—showing a big loss (maybe 100 dB) from walls or distance. To fix it, check the device’s location: if it’s far from an AP or behind thick walls, move the AP closer, elevate it, or add another (like a Ruckus H series for tight spots). Target -67 dBm or better for solid performance.
Q: What’s the difference between signal strength and signal quality? I see both in my system.
A: Good catch! Signal strength (dBm) is how loud the Wi-Fi signal is when it hits a device—like a flashlight’s brightness. You’ll see it as RSSI (e.g., -60 dBm in HP Aruba Central or Ruckus ZoneDirector). Signal quality (often a percentage or SNR) is how clear it is against background noise—like hearing someone over chatter. A strong -50 dBm signal can still stutter if interference from other networks muddies it. Check both: if strength is fine but quality’s low, adjust channels (e.g., in Meraki’s “Radio Settings” or Ruckus’s “Configure > Radio”) to cut through the noise.
Q: Why do some rooms have great Wi-Fi while others are terrible, even with the same AP?
A: That’s signal loss at work. Walls, floors, and stuff in the way sap your Wi-Fi’s strength. A device next to a Fortinet FortiAP might hit -40 dBm (great), but one two rooms over through brick could drop to -75 dBm (poor). Every 3 dB loss halves the power, and a solid wall might steal 10-20 dB. Map your space: center APs (like a Ruckus R750), avoid metal obstacles, and add units for dead zones like far-off offices or gymnasiums.
Q: My users complain about slow Wi-Fi, but the signal is -65 dBm. Isn’t that good enough?
A: At -65 dBm, you’ve got a fair signal—solid for basic tasks like email or browsing—but it might not handle streaming or video calls well, especially with many users. The problem could be capacity or interference, not just strength. Peek at your AP’s client load (e.g., in Ubiquiti UniFi’s “Devices” or Ruckus One’s “Access Points”). If 30+ devices are on one AP, it’s swamped—add another. Also, check interference (SNR in Aruba or “Noise” in Ruckus); if it’s high, tweak channels or power for a cleaner signal.
Q: How many APs do I really need? Can’t one cover my whole building?
A: One AP sounds simple, but signal loss limits it. An AP at 20 dBm might fade to -70 dBm or worse after 50-70 dB of loss from distance and walls—too weak for a big area. Plan one AP per 1,500-2,000 square feet in open spaces, or one per section in a school with lots of walls. Cisco Meraki and HP Aruba offer planning tools; for Ruckus, Fortinet, or UniFi, test with a phone app (e.g., WiFi Analyzer) and add APs where signals fall below -67 dBm.
Q: Can I trust the percentage bars instead of dBm numbers?
A: Percentages—like 75% in Ubiquiti UniFi or Ruckus Unleashed—are a quick peek, but they’re fuzzier than dBm. Each vendor maps them differently (e.g., 50% might be -70 dBm in Fortinet, -65 dBm in Meraki), and they skip details like interference. Stick to dBm for precision: -50 dBm is always strong, -80 dBm is always weak, across Ruckus, Aruba, or any system. Use percentages for a fast check, but lean on dBm when digging into issues.
Still Confused? We’re Here to Help!
Wi-Fi doesn’t need to be a puzzle. At Twotrees Technologies, we’ve tackled these challenges with Fortinet, Cisco Meraki, HP Aruba, Ruckus, and Ubiquiti UniFi networks for schools and businesses. Whether you’re adjusting power or hunting weak signals, we’ve got your back. Contact us today, and let’s make your Wi-Fi work as hard as you do!
