Dear Sridhar,
Hope you are doing well.
Please switch-off the VM and then click on the Network settings in the Virtual box and do changes as shown below:
In Adapter 1 keep it as NAT and in Adapter 2 keep it Host only Adapter


Make sure that in the Adapter 2 , Promiscuous Mode is Allow All
Make this above network settings for the all the VMs which you have created.
Please Let me know if you have any further issue regarding this.
Feel free to contact us in case you have any query.