Here is one tutorial on how to setup networking on the main VPS host node server. This is written for the Hyper V , but it can be possible it will work also for other virtualisation like KVM.

For Hyper-V, enable IP forwarding:
1. open command prompt, type
netsh interface ipv4 show int
and take note the Idx value for hyper v nic. (let say 16 in this example)
2. type
netsh interface ipv4 set int 16 forwarding=enabled
(16 is Idx value)
3. After that, choose 1 IP from /28 subnet and put the IP into the nic as secondary IP. This IP will be act as gateway for VPS. (So, cannot be the first and last IP of /28 subnet.)
4. Then, the rest IP (13 usable) can be use freely on VPS.

Here is some related HyperV tutorial: