@azzoug 

If you want to separate VX1800v 2.4Ghz and 5GHz channels you have to disable Smart Connect (Band steering) feature - refer to this post.

  @azzoug 

According to the thread there's a limitation in Easymesh implementation for VX1800v.

You can try to connect the  re700x as a regular RE (i.e. not in Easymesh) to utilize both wireless bands.

  @azzoug 

Hi, I don't think RE650 supports EasyMesh. So I think when it connects to Archer VX1800v, it can only work as a standard non-mesh extender.

Did you see somewhere on the web UI of RE650 or VX1800V said RE650 is connected via EasyMesh?

azzoug wrote

Today I tried the old wifi extender re650..(AC)
and the 5 and 2.4 bulbs lit up normally
in Easymesh mode

as for the extenders re700x and re505x..(AX)
only one band

By the way, even though there is one band/LED displayed on the RE700x/505x, the extenders should still broadcast both 2.4+5 GHz networks.

Thank you very much and best regards.

  @azzoug 

Hi, Thank you very much for the update.

May I know when you purchased RE700x/RE505x?

If you would like to spend a little more time, It is recommended to send an email to support.forum@tp-link.com(please add forum ID# 751696) with the following details and I can ask the senior engineer for further assistance.

some screenshots of the EasyMesh connection speed and signal strength of RE700x(or RE505x) on the web UI status of Archer VX1800v, such as:

Wait for your reply and best regards.