Windows 2012R2 DHCP Relay Agent doesn't recieve all the replies

Hi,

I have a Windows server 2012R2 act as a router (RRAS) between two networks (A, B). I have only one DHCP server (Windows 2012R2) on the network A. So I added the DHCP Relay Agent on the router who relay the DHCP requests from the network B.

On the network B, I have offen 10-20 Linux DHCP clients (VMs on ESXi) boot at the same time. Randomly, some clients can get the good IP adresse from the DHCP relay, and others failed. 

While looking into the stats of the relay agent, the number of "Request recieved" is greater than the number of "Replies recivied".

Thanks for your help

zt