Slow Wi-Fi in Crowded Apartment Buildings

A complaint typical of apartments: the same internet plan as the old house, the same router, yet the speed is far worse, especially in the evening. The cause is rarely the router. In a tall building, floors and walls aren't thick enough to stop signal, so Wi-Fi from dozens of other units reaches yours, and all of it fights over a limited number of channels.

First, see how crowded it is

Install a signal analyser app on an Android phone and count how many networks are visible from inside the unit, and which channels they pile onto. Guide: Wi-Fi signal analyser apps. In a dense block, 30 to 60 networks is normal, and nearly all of them sit on 2.4 GHz.

Also take one measurement that separates two different problems: connect a laptop to the router with a LAN cable and run a speed test at peak hours. If cable gives full speed, only Wi-Fi is the problem, and everything below applies. If even cable is slow, the building's link to the provider is saturated, and that can't be fixed from inside the unit. How to measure: checking your internet speed; background in internet slow at certain hours.

Steps that cost nothing

Move as many devices as possible to 5 GHz

This has the biggest effect in an apartment. The 2.4 GHz band has only three genuinely non-overlapping channels, and in a dense building all three are full. The 5 GHz band has far more channels, and its signal doesn't pass through neighbours' walls as well as 2.4 GHz, which here works in your favour. Apartment units are usually small enough that 5 GHz's shorter range isn't a problem.

If the router uses one name for both bands, devices often pick 2.4 GHz and stay there. Split the names, then connect phones, laptops, and the TV to the 5 GHz one. How to in what band steering is. Leave 2.4 GHz for smart devices that only support it.

Pick a channel manually, don't leave it on auto

Auto picks a channel when the router boots, then stays there even as conditions change. In an apartment, conditions change every evening. Choose manually from your scan: on 2.4 GHz only channel 1, 6, or 11, and on 5 GHz consider DFS channels (52 to 144), usually far emptier because many cheap routers avoid them. Guide: choosing the right Wi-Fi channel.

Narrow the channel width on 2.4 GHz

Set 2.4 GHz to 20 MHz, not 40 MHz. A wider channel is faster in empty air, but in crowded air it collides with more neighbours and ends up slower. On 5 GHz, 80 MHz still makes sense as long as your scan shows the channel is reasonably clear.

Move the router, even in a small unit

In apartments the router often sits by the front door, because that's where the provider's cable enters, which means half its output is wasted into the corridor and the unit opposite. Move it towards the middle of the unit if you can, and keep it away from the fridge, microwave, and reinforced concrete walls. Guide: router placement; interference from appliances in Wi-Fi interference.

Lower the transmit power, don't raise it

It sounds backwards, but it makes sense in a dense building. More power makes your signal audible further away to neighbours, while your phone still transmits weakly and its replies don't get any stronger. All that increases is interference. If your router has a transmit power setting, 50 to 75 percent is usually plenty for one unit and makes the whole building a little quieter. The two-way explanation is in full signal but slow internet.

When free steps aren't enough

• LAN cable for devices that don't move. TVs, consoles, and work computers don't need to be on Wi-Fi. Every device moved to cable is one device that stops fighting for air. Guide: choosing LAN cable.
• A router supporting 6 GHz (Wi-Fi 6E or 7). This is the best answer for apartments: the 6 GHz band is nearly empty, and its short range keeps neighbours' signals out. It requires devices that support it too. Comparison in Wi-Fi 5 vs 6 vs 7.
• A small access point in a distant room, if the unit is long or on two levels. Use a cabled access point, not a repeater, because a repeater adds traffic to already crowded air. Comparison in access point or second router.

What not to do

• Adding a repeater or extender. In a dense block a repeater makes things worse: it uses the same channel twice and adds another signal source for the neighbours. Full reasoning in mesh Wi-Fi vs repeater.
• Buying a high-gain antenna. It flattens the beam horizontally, which is straight into the units on your floor. See external Wi-Fi antennas.
• Hiding your Wi-Fi name. It doesn't reduce congestion at all, and makes life harder for your own devices. See hiding your Wi-Fi name.

If the internet comes from building management

Some apartments provide shared internet and residents can't change the router. In that case: ask whether you may add your own router behind the supplied point, and if not, measure cable speed at peak hours and report the numbers to management. Measurements are far more useful than a general complaint. Your rights as a customer are covered in customer rights when internet is slow, and if you subscribe yourself, contract terms in cancelling a subscription and contract penalties.

The bottom line

In an apartment, the scarce resource isn't plan speed but air. Move as many devices as possible to 5 GHz, pick channels manually, use 20 MHz on 2.4 GHz, move the router towards the middle of the unit, and lower its transmit power. Cable for devices that stay put, and 6 GHz if the budget allows. Avoid repeaters and big antennas; both add to the crowding that is the actual problem.

Frequently asked questions