Hi s_saluja,
My initial thought is an IP conflict possibly, but without knowing your physical network and interface setup we might have a hard time giving you more specific advice. ESXi Standard switches are very basic. There is not much to configure other than MTU. You might also want to check that MAC learning and Forged Transmits are set to accept.
It will also be a good idea to check hardware like your cables, interfaces or ports. If your switch interfaces and NIC ports are SFPs then it is possible you have bad SFP. If not then it might be a NIC port or switch interface that is the problem and you can move the cable to test. NOTE: If you move the cable to another switch interface you will have to configure that switch interface with the same VLAN and setting as the original.
SSH into the ESXi host and look at the VMNIC stats to see if you are dropping packets, CRC errors, etc.
"esxcli network nic stats get -n vmnicX" replace "X" with vmnic number
Could also be firewall related if the connection is going threw a firewall. You could also have a connection flapping further up stream in your network from your ESXi server. Especially if you have internet facing routers/switches
