@Tony My printer model is Epson Artisan 725, here the picture, you can see the security encryption it used. 

The current firmware only have WPA2-PSK[AES] + WPA-PSK [TKIP] as the nearest possible connection for legacy device. I have the printer that uses WPA-PSK [AES], the older TP-Link C7 AC1750 can use...

@Tony If I do that setup AC1750 --- Deco X20 ->> Deco X20 2nd ->> Deco x20 3rd, am I suppose to connect the first Deco X20 wired to AC1750 in order for it to use the mesh system? I am worry I losing...

I saw the new release Deco X20 and given my AC1750 is old, I thought I give this new wifi devices a try and see if it help my streaming 4k video. I still getting wifi in my 1400sqf 2 stories house,...