yes I ran a speedtest, 1) with laptop via ethernet into wall socket 2) with same laptop and cable via TP Link also via wifi give same speed (80-90Mbs)

@Kevin_Z so sorry, it is AC1200 Archer C50 V1 as in the pasted text: Firmware version:0.9.1 3.0 v0045.0 Build 160411 Rel.42416n Hardware version:Archer C50 v1 00000002 Where can I get support for...

I have - but please can you help with instructions for older UI? You suggest "Go to Advanced-system tools-system parameters to edit the duplex, change it to 1000Mbps full-duplex if you have a gigabit...

@Kevin_Z Could you please explain same steps but for old interface? I have Archer C5 V1 (green UI). Firmware version:0.9.1 3.0 v0045.0 Build 160411 Rel.42416n Hardware version:Archer C50 v1 00000002...