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Why is cable Internet often so slow?

Cable network operators market Internet access with up to 1 gigabit per second (GBit/s). But what sounds like high speed is sometimes pretty slow. Especially in the evening hours, for example, there can be picture and sound dropouts when streaming.

For a long time, the cable network only delivered television and radio. But with high Internet bandwidths, cable network operators are now outstripping the Digital Subscriber Line (DSL). While a household receives a maximum of 250 megabits per second (MBit/s) via a DSL connection, cable Internet offers up to 1,000 MBit/s, i.e. gigabit speeds. The pitfall lies in the “up to” because the booked bandwidth is only achieved under almost ideal conditions with both DSL and cable Internet. This is due to the network structure. A certain bandwidth is made available for a certain number of households, which the connected households have to share. This is referred to as a shared medium. And this circumstance means that cable Internet is often much slower, despite the promised high bandwidths.

The cable network as a shared medium

The shared medium effect can be compared to a highway. If only one car is driving on a certain stretch, the driver can step on the gas. However, if thousands of cars are on the road, the average speed drops.

This also applies to the data highway. Instead of cars, the cable network is about connected households. They are grouped together in what are known as clusters. For each cluster, a specific total bandwidth is available, which the households share.

Too large a cluster, too many users

But if the DSL network is also a shared medium, why do we hear the term so often in connection with cable networks? Cable operators have become victims of their own success. Too many households have booked cable Internet too quickly. According to ANGA, the association of cable network operators, the number of customers has risen by 40 percent to 8.4 million in the past five years. One in three new customers of ANGA network operators chooses a rate with more than 200 Mbit/s. Around 1.7 million customers have so far booked bandwidths above 400 Mbit/s.

Cable network operators are therefore forced to expand their networks. They are reducing the size of the clusters. As a result, fewer households share the total bandwidth per cluster. However, network expansion is not happening fast enough. And it involves costs that are readily avoided in the fierce competition with DSL providers. As a result, the clusters are too large, too many households share the total bandwidth, and cable Internet is too slow.

Cable Internet users feel this especially in the evening hours, when a particularly large number of households go online. Those who were first stuck in a traffic jam on the freeway after work then find themselves in the rush hour of the data highway. The sharp increase in the use of digital applications such as video conferencing or streaming in the Corona pandemic has recently exacerbated the problem for cable Internet users.

Perform speed test and check router

Anyone whose cable Internet is regularly too slow and who thus has to deal with picture and sound problems when streaming, dropouts when online gaming or long download times should carry out a speed test of their Internet connection. The broadband measurement of the Federal Network Agency is recommended. It is best to carry it out at different times of the day. This allows you to see when the bandwidth drops particularly sharply.

However, if the bandwidth is consistently too low, the problem could also be an outdated router. If the router’s network ports only operate at 100 MBit/s, an Internet tariff with 200 MBit/s or more is of little use.

Also interesting: How much Internet speed do I really need?

Request support, change provider

In addition, streaming problems or long downloads can also be related to the number of devices that are online in parallel in the household. Cable Internet at 50 MBit/s may not be sufficient when streaming to three devices at the same time. If the cause cannot be determined, the cable network operator’s support should be consulted.

Be careful if the conclusion of a tariff with more bandwidth is recommended. This may not be very helpful, because the shared-media effect does not decrease if more bandwidth is demanded in the same cluster. In that case, the only solution is to switch providers.