A hybrid network end system device for a network system, comprising: - an end system unit; - a switch, - a control unit; wherein: - the switch has at least one first port of the switch, a second port of the switch for connection with the network system, and a third port of the switch for communication with a first port of the end system unit; and wherein - the end system unit comprises a first port of the end system unit for communication with the switch and a second port of the end system unit for communication with the network system; and wherein - the control unit is designed to switch the switch into a first or a second mode; wherein - in the first mode, the switch is operated to relay data received at the ports (103, 104) of the switch according to their content to a respective responsible port in a star topology, and - in the second mode, the switch is designed to relay data received at the first port of the switch to the end system unit via the third port of the switch, and relay data received at the third port of the switch to the first port of the switch, such that a ring arises between the first port of the switch and the second port of the end system unit. - wherein, if the control device has switched the switch into the second mode, the end system unit is set up to relay data received at the first port of the end system unit to the second port of the end system unit, and relay data received at the second port of the end system unit to the first port of the end system unit. - an end system unit; - a switch, - a control unit; wherein: - the switch has at least one first port of the switch, a second port of the switch for connection with the network system, and a third port of the switch for communication with a first port of the end system unit; and wherein - the end system unit comprises a first port of the end system unit for communication with the switch and a second port of the end system unit for communication with the network system; and wherein - the control unit is designed to switch the switch into a first or a second mode; wherein - in the first mode, the switch is operated to relay data received at the ports (103, 104) of the switch according to their content to a respective responsible port in a star topology, and - in the second mode, the switch is designed to relay data received at the first port of the switch to the end system unit via the third port of the switch, and relay data received at the third port of the switch to the first port of the switch, such that a ring arises between the first port of the switch and the second port of the end system unit. - the switch has at least one first port of the switch, a second port of the switch for connection with the network system, and a third port of the switch for communication with a first port of the end system unit; and wherein - the end system unit comprises a first port of the end system unit for communication with the switch and a second port of the end system unit for communication with the network system; and wherein - the control unit is designed to switch the switch into a first or a second mode; wherein - in the first mode, the switch is operated to relay data received at the ports (103, 104) of the switch according to their content to a respective responsible port in a star topology, and - in the second mode, the switch is designed to relay data received at the first port of the switch to the end system unit via the third port of the switch, and relay data received at the third port of the switch to the first port of the switch, such that a ring arises between the first port of the switch and the second port of the end system unit. - wherein, if the control device has switched the switch into the second mode, the end system unit is set up to relay data received at the first port of the end system unit to the second port of the end system unit, and relay data received at the second port of the end system unit to the first port of the end system unit.