Perfect at ten in the morning, unwatchable at eight at night, and back to normal by midnight. A problem that follows the clock that closely is congestion, and the useful question is whether the congestion is inside your house or outside it, because those have completely different answers.
The short answer
Run a speed test on ethernet at a good time and again at a bad time. If the line speed itself collapses in the evening, the congestion is outside your house and it is your provider’s. If the line holds up and only Wi-Fi degrades, the congestion is neighbouring Wi-Fi networks and you can fix it by changing channel or moving to 5 GHz.
Two different kinds of evening congestion
- Broadband contention. Your connection is shared with neighbours at some point in the network, and when everyone streams at once the capacity is divided. This shows up as your measured line speed falling in the evening.
- Wi-Fi congestion. Every neighbouring household’s Wi-Fi is busier in the evening, and on the crowded 2.4 GHz band they interfere with each other. This shows up as Wi-Fi degrading while the line itself is fine.
Telling them apart takes one ethernet cable and two speed tests, and it determines whether the fix is something you can do or a conversation with your provider.
Test on ethernet at a good time
Connect a laptop by cable directly to the router in the morning and note the speed. This is your baseline for what the line delivers when it is quiet.
Test on ethernet again at the worst time
Same cable, same laptop, same test. If the number has collapsed, the line is congested and the problem is outside your house.
Test on Wi-Fi at both times too
Now you have four numbers. If ethernet holds up and Wi-Fi collapses, neighbouring networks are the cause and that is fixable at your end.
Scan the Wi-Fi channels in the evening
Use an analyser app at the worst time. You will usually see many networks stacked on the same 2.4 GHz channels. Move yours to whichever of channels 1, 6 or 11 is least used.
Move devices to 5 GHz
Far less congested than 2.4 GHz because it has more channels and shorter range, meaning fewer neighbours reach you. This is the single most effective fix for evening Wi-Fi congestion.
Check what else in your house is running
A console downloading, a cloud backup, another 4K stream. Household congestion looks identical to neighbourhood congestion and is much easier to fix.
Enable smart queue management on the router
If one device downloading ruins everyone else’s streaming, your router is queueing badly. SQM keeps queues short and shares capacity properly.
Log the pattern before contacting your provider
If the line itself degrades, record dates, times and speeds for a week. A documented pattern gets taken seriously; a general complaint does not.
The four-measurement grid, ethernet and Wi-Fi at both a good and a bad time, answers the whole question in half an hour and tells you definitively whether to change your Wi-Fi channel or phone your provider. Without it you are guessing, and the two causes look identical from the sofa.
If the line is the problem
Contention is a design feature of most consumer broadband: capacity is shared on the assumption that not everyone uses it at once, and in the evening that assumption fails. Some of this is normal and some of it is excessive.
What you can do: report it with your log of measurements, because providers do act on documented evening degradation and sometimes rebalance capacity. Ask specifically whether your area is known to be congested. And check whether a different technology is available at your address, since a connection type with less sharing behaves very differently in the evening.
Do not upgrade your broadband plan to fix evening congestion without establishing the cause first. If the constraint is contention, a faster plan shares the same congested capacity and changes very little. If it is Wi-Fi, a faster plan changes nothing at all.
If Wi-Fi is the problem
This is the more common case and the better news, because you can fix it. The 2.4 GHz band has three non-overlapping channels and in a flat or a terrace there may be twenty networks sharing them. In the evening, when everyone is home and streaming, that band becomes genuinely unusable.
The fixes, in order: move everything capable to 5 GHz, which has many more channels and shorter range so fewer neighbours reach you; set your 2.4 GHz network to the least crowded of channels 1, 6 or 11; and put the television or streaming device on ethernet, which removes it from the contest entirely.
Why is my internet slower in the evening?
Either your broadband is shared with neighbours and everyone is using it, or neighbouring Wi-Fi networks are congesting the airwaves. Testing on ethernet separates the two.
How do I know if it is my Wi-Fi or my provider?
Test on an ethernet cable at a good time and a bad time. If the line speed itself collapses, it is your provider. If it holds up and only Wi-Fi is bad, it is neighbouring networks.
Will a faster plan fix evening congestion?
Only if your line genuinely runs out of capacity for your own use. If the cause is contention or Wi-Fi congestion, a faster plan changes little or nothing.
Why is 5 GHz less congested?
It has many more channels and shorter range, so fewer neighbouring networks reach you. Moving devices to it is the most effective fix for evening Wi-Fi congestion.
Is there any point complaining to my provider?
With a week of logged measurements, yes. Providers do act on documented evening degradation. A general complaint without data rarely goes anywhere.
The bottom line
Take four measurements: ethernet and Wi-Fi, at a good time and a bad time. That grid tells you definitively whether the congestion is yours to fix or your provider’s. If it is Wi-Fi, move to 5 GHz and change your 2.4 GHz channel. If it is the line, log a week of numbers before calling, because that is what gets acted on.
