GS748Tv5 / GS750E : LAG Issue

Hello,

 

I have an issue to create a LAG between two switch ( GS748Tv5 & GS750E)

 

I have a switch GS748Tv5 (named MRK) witch have several computer (Desktop) connected, a NAS (named WINWIN3D) and a internet box. And i have an other switch GS750E (named RDF) witch have other computers (Render) connected.

I'm able to create a LAG (4 ports) for NAS (WINWIN3D) and Desktop can access to WINWIN3D and internet.

 

But when i want to create a LAG (4 ports) between MRK and RDF, le LAG is UP but i don't have acess to WINWN3D, neither internet for Render computer.

 

LAG is LACP, All ports are configured on VLAN 1 by default (LAG inclued)

 

(I have an other switch GS748Tv4 (named VR) connected to switch (MRK) with LAG (6 ports) and it works fine. This switch (VR) has 3 NAS connected with LAG (4 ports) each and Desktop connected to MRK can access to NAS connected to VR.)

 

Do you have any idea where is the issue ? And how to fix it ?

 

Thanks

 

Baptiste