In a row of flats or an office block, your WiFi is shouting in a room where twenty routers shout back. Channel and width settings decide whether yours is heard — and the defaults are frequently wrong for crowded air.
Every WiFi network shares public air. Your router's channel is the lane it picks; the channel width is how many lanes it spreads across. Wide sounds faster, and on an empty road it is. In a crowded lane, wide just means more neighbours' traffic inside your signal — and theirs inside yours. These settings live under Wireless → Wireless Settings for each band.
The 2.4 GHz band's channels overlap heavily: channel 3 sits on top of both 1 and 6 and argues with everyone. Only 1, 6 and 11 stand clear of each other, so a network on any in-between channel creates interference without gaining a clean lane. Open the router's wireless page (or any WiFi analyser app on your phone), look at which of the three is least used by neighbours, and set yours there manually. If all three are busy, pick the one whose strongest neighbour is weakest — signal strength matters more than the count of names.
Width 40 MHz doubles the theoretical lane — by consuming the space of two of the three clean channels. In a detached house with no neighbours, enjoy it. In a flat or an office floor, your 40 MHz network overlaps everyone, receives interference from all of them, and spends its life retransmitting. Setting 20 MHz looks like a downgrade and behaves like an upgrade: fewer retries, steadier latency, and speed that survives the evening peak when every neighbour streams at once.
The 5 GHz band has many more channels and walls weaken it quickly, so crowding is rarer and 80 MHz width usually delivers the AC1900 class's real speed to a nearby laptop. Drop to 40 MHz if a specific room's connection is unstable or a neighbour's 80 MHz block sits exactly on yours — the scan shows it. Leave the channel on a fixed choice rather than Auto if you find one clearly emptier block: Auto re-scans can also hop your network mid-day when a radar-detected (DFS) channel gets vacated around airports and weather radars.
Auto sounds intelligent; in practice the router samples the air once at boot — often at 7 AM when the neighbourhood is asleep — and keeps that channel through the crowded evening. A manual choice made from an evening scan beats it. Leave Auto only if your area is genuinely empty of other networks, or if you reboot so rarely and suffer so little that the setting does not matter.
Watch the wireless pages and channel settings on the real router in the full setup video.
▶️ Watch Full VideoNo — channel 3 overlaps 1 and 6, so you would fight both the channel 1 and channel 6 networks at once, plus everyone between. Sharing channel 6 cleanly is genuinely better: routers on the same channel can hear each other and take turns, while overlapping channels just corrupt each other's frames.
It increases the share of your plan's speed that survives the air. If your plan is 100 Mbps and interference was costing you half the evening throughput, a clean channel can feel like a plan upgrade. It cannot exceed the plan, and it cannot fix a slow line — test wired once to know which problem you actually have.
With no neighbours in range, 40 MHz on 2.4 GHz and 80 MHz on 5 GHz are both fine and faster on paper. The crowded-area settings in this guide are a response to interference, not a universal law — scan first, then decide.