Wi-Fi diagnosis
Slow Wi-Fi on iPhone: How to Tell Whether the Problem Is the Signal or the Plan
You pay for hundreds of megabits, but the iPhone in the bedroom will not open videos or freezes on calls. Find out how to test the difference between rooms and find the root cause.
Frequency comparison
The practical difference between 5 GHz and 2.4 GHz.
Understand why your iPhone can show full Wi-Fi signal and still deliver a slow connection.
| Characteristics | 5 GHz network (Recommended) | 2.4 GHz network (Legacy) |
|---|---|---|
| Radio frequency | 5 GHz (High frequency) | 2.4 GHz (Low frequency) |
| Real download speed | Up to 800+ Mbps at your plan’s full speed | Limited to ~40–70 Mbps in practice |
| Wall penetration | Low; suffers strong attenuation from barriers | High; passes through several walls and slabs |
| Useful physical range | Up to 1 or 2 rooms with line of sight | Covers outdoor areas and distant rooms |
| Electromagnetic interference | Almost none; dozens of clean channels | Heavy (microwaves, Bluetooth, neighbors) |
| When to prioritize on iPhone | Video calls, games and 4K streaming | IoT devices and emergency use in blind spots |
Physics of materials
How walls absorb the signal.
Radio signal loses power at every obstacle it meets. While drywall causes little loss, solid concrete and tiles call for extra nodes or a wired connection.
Part 1 of 4
Why is the internet slow only in some rooms?
It is common to blame the provider when browsing on the iPhone gets slow. In most cases, however, the fiber delivers the contracted speed at the modem.
The bottleneck is almost always the physics of the Wi-Fi signal. Masonry walls, tiles, mirrors and doors weaken the signal as you move away from the router.
The iPhone also manages its antenna with battery life in mind. In weak-signal areas it lowers receive power so the device does not overheat.
Good to know
Attenuation from barriers
Masonry walls and tiles (kitchens and bathrooms) cut the Wi-Fi signal by up to 70% of its original strength.
Part 2 of 4
The comparison test: how to isolate the cause
To know with scientific precision whether the problem is your connection from the street or the wireless coverage in your home, run the 2-step test:
Stand about 1 to 2 meters from the main router, with a direct line of sight. Open Linka and run a full measurement (latency, download and upload).
Go to the room where you notice slowness (e.g., bedroom or office) and run exactly the same test.
Compare the two results in History. If the measurement next to the router delivered 90% to 100% of your plan and the bedroom dropped by more than 50%, your plan is healthy: the problem is purely Wi-Fi coverage.
Part 3 of 4
The 2.4 GHz vs 5 GHz trap
Modern routers usually broadcast two distinct radio frequencies:
- 5 GHz network: Extremely fast with low latency, ideal for 4K streaming, FaceTime meetings and games, but with a shorter range that suffers from walls.
- 2.4 GHz network: Longer range and better wall penetration, but far less bandwidth and prone to interference from microwave ovens and cordless phones.
Many providers set up a single network with automatic "Band Steering". If your iPhone is silently switching to the 2.4 GHz band because of distance, your speed will drop from 400 Mbps to 30 Mbps even though the signal shows "full".
Practical tip
Practical tip
If your router allows it, separate the network names (e.g., Home_5G and Home_2.4G). On the iPhone, always connect to the 5G network where you work or watch streaming.
Part 4 of 4
Practical steps to recover the signal
Raise the router: Never leave the equipment on the floor or inside closed cabinets. The ideal height is between 1.20 m and 1.80 m off the ground.
Centralize the access point: Placing the router in the room where the fiber enters (often at the edge of the property) creates blind spots at the other end.
Add mesh nodes: For homes over 70 m² or with several floors, ordinary plug-in extenders just clone a degraded signal. A mesh system with dedicated backhaul is the definitive solution.
Two-step diagnosis
Isolate the cause of slowness on your iPhone.
Take one measurement next to the router and another in the distant room to compare the signal lost through walls.
Reference measurement (Near the router)
Stand 1 meter from the modem with a direct line of sight to capture the real capacity arriving from the fiber.
Attenuation measurement (in the problem room)
Go to the bedroom or office with slowness and repeat the test to record the loss caused by walls.
How to read the relationship between the two tests:
Physical signal attenuation (Walls)
Your provider’s link is healthy. The loss in the room comes purely from walls absorbing the signal. A mesh network or separating the 5 GHz network solves this bottleneck.
Linka for iOS
More than speed. Clarity about your connection.
Browsers cannot analyze radio channels or the physical distance to your antenna. The native iPhone app was built to map network behavior in each room.
Point your iPhone camera hereRoom-by-room diagnosis
Label tests like "Living room" and "Office" to compare attenuation and signal loss between rooms.
Clear verdicts with Assist
Find out whether your connection supports video calls and games, in human language, without indecipherable jargon.
Absolute privacy on iPhone
No sign-up, no ads and no tracking of personal data. Your history stays on the device.
Common questions
Frequently asked questions.
Direct, technical answers to the most common questions about connection and Wi-Fi.
It can help if the DHCP cache or local DNS routing is corrupted, but it will not change the physical attenuation of the signal or obstacles between the iPhone and the router.