Slow connection

Cable

One reason for a slow connection can be the cable. There is usually an inscription on the cable that indicates the type of cat (category type).

UTP Category Data Rate Max. Length Application
CAT1 1 Mbps - Old Telephone Cable
CAT2 4 Mbps - Token Ring Networks
CAT3 10 Mbps 100m Token Ring & 10BASE-T Ethernet
CAT4 16 Mbps 100m Token Ring Networks
CAT5 100 Mbps 100m Ethernet, FastEthernet, Token Ring
CAT5e 1 Gbps 100m Ethernet, FastEthernet, Gigabit Ethernet
CAT6 10 Gbps 100m GigabitEthernet, 10G Ethernet (55 meters)
CAT6a 10 Gbps 100m GigabitEthernet, 10G Ethernet (55 meters)
CAT7 10 Gbps 100m GigabitEthernet, 10G Ethernet (100 meters)

Quelle

Router

Hardware

The router may not support the desired speed. This is best found in the data sheet of the router.
For example, the following speeds can be found for the two TP-Link routers:
TL-WR940N:

Archer C6:

Software

Some routers offer limiting functions, for example to implement prioritization.
Here is an example for the previously mentioned TP-Link routers:
TL-WR940N:

Archer C6: