@Oneacer 

Hi, Straight-through Ethernet cables are the most commonly used. I think it would be fine to create Ethernet Backhaul between two Deco X55s.

Thank you very much and best regards.

  @Oneacer,

To add on here, you really will never come across crossover cables unless you need to wire or connect to servers directly, or when connecting two devices together that you do not think should go together (ie. PC to PC). For Decos, the satellites all act as clients of the main node, meaning that you would connect these nodes into your network, the same way that you would connect a PC or other wired client device.

For the most part, any regular consumer application will use the typical T568A or T568B, with matching connections on both ends.

Both standards are used and neither is technically a crossover - as long as both ends of the cable match in order / type, your cable will be seen as valid.

I would recommend choosing one of the two standards and using that across your entire home.