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.
I think this will resolve your query.
Please Let me know if you have any further issue regarding this.
Feel free to contact us in case you have any query.