If your Wi-Fi shows full bars but still feels slow, drops video calls or grinds to a halt when the office fills up, the culprit is often not your broadband at all. It is cross-channel interference: too many wireless signals fighting over the same airwaves. Here is what it is, why it matters, and how to fix it for good.
What cross-channel interference actually is
Wi-Fi does not have unlimited room to work in. It runs over a set of radio channels within the 2.4GHz and 5GHz bands, and 6GHz on the newest kit. When two access points, or your network and a neighbour’s, transmit on the same or overlapping channels, their signals collide. Devices then either have to wait their turn, known as co-channel interference, or try to make sense of a signal drowning in noise, known as adjacent-channel interference. The 2.4GHz band is especially cramped, with only three channels that do not overlap, so it fills up fast.
Why it makes your Wi-Fi feel slow
Interference rarely shows up as “no signal.” It shows up as a network that looks fine on paper but performs badly:
- speeds that are a fraction of what you pay for;
- video calls and Teams meetings that stutter and drop;
- pages that hang and files that crawl;
- devices that cling to a weak access point instead of moving to a better one; and
- everything getting worse as more people and devices connect.
It is one of the most common reasons a business is convinced its broadband is the problem when the broadband is actually fine.
What causes it in real buildings
In practice it builds up from a mix of things:
- too many access points, or consumer routers, all shouting on the same channels;
- everything crammed onto the busy 2.4GHz band;
- access points turned up to full power, so their coverage overlaps badly;
- wide channel settings that use up the limited space;
- neighbouring businesses and flats whose Wi-Fi bleeds into yours; and
- a network that grew piecemeal, with kit added over the years and never planned as a whole.
How to resolve it properly
The fix is not a bigger router, it is a properly designed network:
- a site survey to see exactly where signal and interference are, before anything is installed;
- a proper channel plan, using the non-overlapping channels and leaning on the roomier 5GHz and 6GHz bands;
- sensible channel widths and transmit power, so access points cover their area without trampling each other;
- the right number of business-grade access points in the right places, rather than a few over-stretched ones;
- band steering to move capable devices onto the faster, quieter bands; and
- centrally managed access points that tune themselves and can be adjusted remotely, with ongoing monitoring so new interference is spotted and fixed.
How Synergy Max can help
This is exactly what our Networks & Wi-Fi service is built for. We start with a proper survey and design rather than guesswork, install business-grade access points from the likes of Ruckus, UniFi and Omada, and set the channels, power and bands up correctly for your building and the way you use it. Because the kit is centrally managed, we can monitor it and make changes remotely, so if interference creeps back in we deal with it before it becomes your problem. And when someone says the internet is down, we can tell you straight away whether it is really the line or the network, and put it right.