PVS 7.15 - Unable to boot target devices due to TFTP timeout error

While booting up PVS 7.15 target devices, it fails with "PXE - E32: TFTP open timeout"...

Error: "Connection Timed Out (0x4c126035) When Connecting to vDisk on Citrix Provisioning Services

Error 1 : "Connection timed out 0x4c126035 with tftp://0.0.0.0/ARDBP32.bin"" Error 2 :"Could not boot from file name “ARDP32.bin”"...