To enable the Acronis PXE Server to work in another subnet (across the switch), configure the switch to relay the PXE traffic. The PXE server IP addresses are configured on a per-interface basis using IP helper functionality in the same way as DHCP server addresses. For more information please refer to: https://support.microsoft.com/en-us/help/257579/pxe-clients-do-not-receive-an-ip-address-from-a-dhcp-server.