A phone can report a strong 5G connection and deliver very different speeds a few streets apart. Three separate factors combine to produce that variation.

Bands trade coverage against capacity

Lower frequencies travel far and penetrate buildings well but carry relatively little data, because the available channel width is narrow.

Higher frequencies offer much wider channels and correspondingly higher speeds, while travelling shorter distances and being blocked by walls and even foliage.

A phone showing a 5G indicator may be on any of these, and the speed difference between the extremes is far larger than the indicator suggests.

Capacity is shared within a cell

Everyone connected to the same cell draws from the same pool of capacity, so measured speed falls as the number of active users rises.

This is why the same location tests quickly at night and slowly during a commute, with no change in signal strength.

Dense areas receive more cells to compensate, which is the main reason coverage maps and speed maps look so different from each other.

The connection behind the cell matters

Each site is linked back to the core network by a fibre or microwave connection, and that link has a finite capacity shared by everyone on the cell.

Where a site is fed by an older or lower-capacity link, the radio can be capable of far more than the site can actually deliver.

Upgrading these links is expensive civil work, which is why capacity improvements lag radio upgrades in many places.

Some 5G runs on 4G infrastructure

Many deployments attach 5G radio to an existing 4G core, which improves data rates while leaving connection setup and control on the older system.

Networks built with a 5G core handle those functions natively, which reduces response times and enables features that the combined arrangement cannot support.

Both display the same indicator on a phone, so users cannot tell which they are on from the interface.

Indoors is a different problem

Modern building materials attenuate higher frequencies heavily, and coated glass in particular is close to opaque at those wavelengths.

A phone indoors therefore often falls back to a lower band, which is why speeds drop sharply on walking through a door.

Dedicated indoor equipment addresses this in large venues, and it is why coverage inside a stadium can be better than on the street outside.