@Milad1993xx  Hello, 

I'm afraid the exact chipset model is not open to customers but here are some other information that may help: 

VR400 V3 uses a different chipset from V2 ,and  here are the main differences: 
Hardware:

1) V3 adopts a new appearance 

2) V3 upgrades the Ethernet ports to 4* 1000  LAN Ports    vs  V2 has 1* Gigabit LAN port + 3 *100  LAN ports

Software : 

VR400 V3 supports oneMesh feature on software  vs  V2 does not support oneMesh

The overall performance on V2 & V3 are of the same level and the basic software functions and wireless specs are the same on V2 and V3.

For details, you could compare the Datasheets of V2 and V3: 

https://www.tp-link.com/support/download/archer-vr400/v3/

Hope this could help ~