You can use same vswitch for multiple virtual machines.
So, one physical interface (or multiple aggregated interfaces in one) -> one vswitch -> multiple VM's.
I suspect that the network is not configured properly on VM that is not working.
Check route table
netstat -rn, and if also check if DNS is working properly (resolv.conf, nsswitch.conf)
Also for network presistence configure the
/etc/rc.config.d/netconf with address and gateway on the VM in question or use sam / smh for the same.
Hope that helps, if not, i can offer some additional support when i come back from vacation
in about 10 days.