This is my setup

ONU > Deco X20 Gateway > TL-SG108E > LS1005G > Deco X20 AP

When removing the TL-SG108E from the picture.
Everything works fine and sweet.

After adding the TL-SG108E, everything breaks down behind it.
My PS4 and smart TV to used to work fine with the LS1005G over Ethernet before I got the TL-SG108E as it doesn't need any configuration.

Pls advise what configuration should be done on the TL-SG108E for everything behind it and plugging to itself works

Thanks