Hello, Im not sure if this is the place where I can ask this since i am using Maxis Broadband DSL
If this is not the place then i am sorry

recently my old router just KO due to dramatic speed decreased overtime
so i bought a new router TP WR-841N (even changed to new Cat6 Lan Cable i got from KopiPeng)
Im currently using the normal RM88 Maxis Broadband so i have the DSL Modem provided from Maxis years ago (Zxyel P-660)

If I setup normally
Modem -> Wan Port Router -> PC

my PC wont see the connection even after quick setup, during quick setup, the wizard are unable to identify the connection type

If I setup Modem -> PC
direct cable i will get the full glory of all the internet
but wont be able to connect other PCs/Laptops/Phones

Recently i found some video explaining to turn the router into a switch
which i did by turning off the DHCP Server within the router itself
Modem -> Lan Port Router -> PC/Laptops/Phones
but the speed decreased dramatically, speedtest shows bad download speed 70% lower then the original speed for cable, 90% lower for wireless

Is there something i can do about it?
Please guide me sifu