Why Is My WiFi Slow? Quick Checks

Updated: 2026-11-03 · 6 min read

Slow WiFi rarely has one dramatic cause. It's usually a pile of small things: a router behind the TV, an old phone hogging airtime, a neighbour's network on the same channel. The trick is checking them in the right order so you fix the real problem first.

Step 1: Measure, don't guess

Start with two speed tests:

1. Right next to the router.
2. In the room where it feels slow.

Then compare with your plan's advertised speed. This one comparison tells you where to look:

• Slow next to the router too: the problem is likely the internet connection, the router itself or something using the bandwidth.
• Fast near the router, slow elsewhere: it's a WiFi coverage problem.
• Fast on one device, slow on another in the same spot: it's the slow device.

If the numbers confuse you, read Internet Speed Test: What Download and Upload Mean first. On Android, Wifi QR Connect has a download/upload speed test and shows current WiFi connection info, so you can test room by room and confirm which network you're actually connected to. It also scans and creates WiFi QR codes and shares hotspots by QR.

Step 2: Restart properly

It's a cliché because it works. Restarting clears memory leaks, stuck processes and overheating:

1. Unplug the modem (or ONT/fibre box) and the router (if separate).
2. Wait 30 seconds.
3. Plug in the modem first, wait until its lights are steady, then plug in the router.
4. Restart the slow device as well.

If a restart fixes it but the problem keeps returning every few days, check for router firmware updates or consider replacing an old router.

Step 3: Look for bandwidth hogs

Something on your network may be using the connection:

• Game console or PC updates, which can be tens of gigabytes.
• Cloud backups (Google Photos, iCloud, OneDrive) after you've taken lots of photos.
• 4K streaming on multiple TVs.
• Torrent or download managers.
• Security cameras uploading video to the cloud.

Your router's app usually shows which devices are using the most data. Pause the heavy ones and test again.

Step 4: Fix router placement

Router location is the most common cause of weak WiFi at home.

• Put it central and high, on a shelf rather than the floor.
• Keep it out of cupboards and away from TVs, fish tanks, mirrors and metal.
• Avoid placing it right next to microwaves, baby monitors and cordless phone bases, which can interfere with 2.4 GHz.
• Point external antennas in mixed directions (one vertical, one horizontal) for better coverage across floors.

Concrete walls, common in many homes, block WiFi heavily. Each thick wall can cut speeds significantly.

Step 5: Choose the right band

Most routers broadcast two bands, and some newer ones three:

• 2.4 GHz: longer range and better through walls, but slower and more crowded.
• 5 GHz: much faster at short and medium range, weaker through walls.
• 6 GHz (WiFi 6E/7): very fast, low interference, shortest range, and only on newer devices.

If your router uses one name for all bands (band steering), devices pick automatically. If you have separate names, connect to 5 GHz in rooms near the router and 2.4 GHz only where 5 GHz is too weak.

Step 6: Reduce interference

In apartments, dozens of networks may compete for the same channels.

• Let the router choose channels automatically, or use its app's "optimise" feature.
• On 2.4 GHz, channels 1, 6 and 11 are the ones that don't overlap.
• Use 20 MHz channel width on 2.4 GHz for stability; wider widths on 5 GHz for speed.
• A WiFi analyser app can show which channels nearby networks use.

Step 7: Check the device

Older devices slow down everyone:

• Phones and laptops more than six or seven years old may only support WiFi 4 (802.11n), which limits speeds.
• Too many saved networks or a bad saved profile can cause problems. Forget the network and rejoin; with a QR code this takes seconds. See How to Scan a WiFi QR Code on Android or on iPhone.
• Update the device's software and, on laptops, the WiFi driver.
• Turn off battery saver modes that may limit network performance.
• VPNs can slow your connection; test with the VPN off.

Step 8: Check security and unknown devices

Unexpected devices on your network use bandwidth and are a security risk.

• Open your router app and look at connected devices.
• If you see unknown ones, change your WiFi password, then reconnect your devices and print a new QR code: How to Change Your WiFi Password and Update QR Codes.
• Make sure security is WPA2 or WPA3, not open or WEP. See WPA2 vs WPA3.
• Move visitors to a guest network with an optional bandwidth limit: How to Set Up a Guest WiFi Network.

Step 9: Extend coverage the right way

If the router is well placed and some rooms are still weak:

• Mesh WiFi systems use two or three units to cover a home with one network name. They're usually the best option for multi-floor houses.
• Access points connected by Ethernet cable give the best performance if you can run a cable.
• Powerline adapters with WiFi can work in homes where cables are impractical, though results depend on your electrical wiring.
• Simple range extenders are cheapest but often halve speed and may create a separate network name. Place them halfway between the router and the dead zone, not inside it.

Step 10: Know when it's the provider

If, with a cable plugged into the router and other devices paused, you still get much less than your plan at various times of day, the issue is likely the connection itself. Before calling:

• Note several test results with dates and times.
• Check your provider's app or website for outages.
• Inspect cables and the fibre or DSL connection for damage.
• Ask whether your router or modem is outdated for your plan speed; many providers will replace old equipment.

Quick checklist

1. Speed test near the router and in the slow room.
2. Restart modem and router.
3. Pause big downloads and backups.
4. Move the router to a central, open, high spot.
5. Use 5 GHz nearby.
6. Change channel or let the router optimise.
7. Update device software; forget and rejoin.
8. Check for unknown devices; change the password if needed.
9. Add mesh or an access point for distant rooms.
10. Call the provider with your test results.

FAQ

Why is my WiFi slow but my mobile data is fast?

It's usually a home issue: router placement, interference, an overloaded router or a problem with your broadband line. Test next to the router and with a cable to narrow it down.

Why is my WiFi slow only at night?

Evenings are peak usage times, both in your home and on your provider's network. Neighbouring WiFi networks are also busier, which increases interference.

Does restarting the router really help?

Often, yes. It clears temporary faults and memory problems. If you need to restart frequently, update the firmware or consider a newer router.

Is 2.4 GHz or 5 GHz faster?

5 GHz is faster at short to medium range. 2.4 GHz reaches further through walls but is slower and more prone to interference.

Can too many devices slow down WiFi?

Yes. Each active device shares airtime and bandwidth. Older devices can slow the whole network, so update or move them to a guest network where practical.