1) For items with LEDs, check if the switch's network LED (green) is lit normally.
    It lights up quickly during normal network operation.
    If it does not light up properly, the port may be defective and change it to an empty port.
    If the defect occurs even when connecting to an empty port, replace the POE SW equipment.

2) You should check the RJ45 working condition of the UTP line and whether it is corroded or burnt.
    If it is defective, you should replace the RJ45.

3) The connection between switches is Gigabit in the case of optical cables, and can be up to 2km long depending on the environment.
    In the case of UTP lines, the maximum is about 100m, and the network speed decreases in inverse proportion to the length as it gets longer

4) Depending on the capacity and characteristics of the switch, using all ports may result in a network load.
    We recommend using up to 70-80% of all ports.