Slow Wi-Fi: what can cause it and what you can check

What the message looks like

Das WLAN ist verbunden, aber Seiten laden zäh und Videos ruckeln.

Common causes

• Too much distance from the router, or thick walls and floors in between, weaken the signal.
• On 2.4 GHz, neighbouring networks, Bluetooth, microwaves or baby monitors interfere. This band is often crowded.
• The device sits on 2.4 GHz although 5 GHz is available. 5 GHz usually has less interference but shorter range.
• Many devices use the network at once, for example streaming, downloads and updates.
• The router is badly placed, for example in a cabinet, on the floor or behind the TV.
• The problem is not Wi-Fi at all but the internet line or DNS.

Check

1. Measure reachability and jitter to the router (Windows; on macOS/Linux use -c 20 instead of -n 20)
   ping -n 20 192.168.178.1Copy
2. Check latency to the internet and compare it with the router value
   ping -n 20 8.8.8.8Copy
3. Show signal strength and band in use on Windows
   netsh wlan show interfacesCopy
4. List nearby Wi-Fi networks and their channels on Windows
   netsh wlan show networks mode=bssidCopy
5. Check that name resolution answers quickly
   nslookup example.comCopy

Fix

• First plug a cable into the router and test. If it is slow there too, Wi-Fi is not the cause: the line or the provider is.
• If only Wi-Fi is slow, move close to the router and test again. A clear improvement points to distance or walls.
• Place the router in the open and raised, not in a cabinet and not next to sources of interference.
• Connect devices near the router to the 5 GHz network. On 2.4 GHz a fixed channel (1, 6 or 11) with few neighbours is often steadier than automatic.
• Restart router and device once and install pending router firmware and Wi-Fi driver updates. Menu names differ by firmware.
• If coverage is not enough, a repeater, a mesh system or a network cable to a fixed device can help.

FAQ

Is a new router the solution?

Not automatically. Position, band and channel often help more than new hardware. Check the points above first.

Why is Wi-Fi slower in the evening?

More devices in your home and the neighbourhood use the radio band and the line. Either can slow things down. A test by cable shows where the problem sits.