@shveikas 

Hi, welcome to the community.

Can you further illustrate that "you get a weak signal (even in the same room, same spot)"? Do you mean the wireless speed on the mobile device is not as fast as when there is only NX510? or has the signal strength dropped, for example from -40dbm to -50dbm?

If you set RE705x to connect Nx510v as a normal wireless extender, not using EasyMesh, will the wireless signal remain as good as before?

Thank you very much and best regards.