4G or 5G home internet: how to test it properly

Updated 23 September 2026

A mobile router can deliver excellent speed, or collapse at 7pm. It all depends on coverage, distance to the mast and how many people are connected at the same time. Here is how to check it properly before committing.

What determines your speed

Factor	Effect
Distance to the mast	The further away, the lower the speed
Obstacles	Thick walls, other buildings, terrain, insulating glazing
Frequency band	Low bands travel far but are slower; high bands do the opposite
Number of users on the mast	Speed is shared: this explains the evening drop
Where the router sits	A few metres sometimes change everything

The test procedure, in five steps

Test in several places. Put the router near a window, then in another room, and measure each time. Keep the setup identical between measurements: Ethernet cable and nothing else running.
Face the mast. Providers' coverage maps and official national tools show where masts are. A window facing that direction usually gives the best result.
Test at several times: morning, afternoon, then between 8pm and 10pm. That last figure matters most, because it is what you get when you most need it.
Note ping and jitter, not just speed. On mobile, latency varies far more than on a fixed line.
Repeat over several days. One good measurement proves nothing.

Mind your data: every test transfers real data, several hundred megabytes on a fast connection. If your plan is capped, space the measurements out.

Reading the router's indicators

Most 4G and 5G routers show signal quality, often as bars or technical values. Two useful ones:

RSRP: the received signal strength. It is negative, in dBm, and the closer to zero the better.
SINR: signal quality against noise. The higher it is, the higher speed can climb.

Move the router while watching these values: they react instantly, whereas a speed test takes time and uses data.

Improving reception

Raise the router, near a window, away from metal furniture.
Try every side of the home: the difference between two windows can be dramatic.
Avoid pressing it against low-emissivity double glazing, which contains a thin metal layer that blocks signal. Testing with the window open tells you whether that is the issue.
Consider an external antenna if your router has connectors for one and coverage is poor.
Lock the frequency band if your router allows it, when one band clearly outperforms another.

Can 4G or 5G replace a fixed line?

Yes, if your evening measurements stay solid over several days, latency is steady, and your plan does not cap data too tightly.

No, if you play competitively online, your job depends on video calls all day, or speed collapses at peak times.

Check three points in the contract as well: any data cap or slowdown beyond a threshold, the priority your plan gets against mobile customers, and the cancellation terms if coverage degrades.

Test my speed now

Frequently asked questions

Why is my 5G excellent in the morning and poor in the evening?

The mast is shared between all its users. At peak times the capacity is split between far more people. That is the main limitation of mobile internet at home.

Can moving the router a few metres really make a difference?

Yes, often dramatically. A load-bearing wall or insulating glazing is enough to sink the signal. Watch the router's indicators as you move it: the reaction is instant.

Does an external antenna genuinely improve reception?

In poorly covered areas, yes, provided your router has antenna connectors and the antenna points at the right mast. Where coverage is already good, the gain is small.