How to setup sharedNAT on lowend VPS?

Question

Network administration

On lowendstock.com was taken for GDS exercises with the condition of providing 20 NAT ports over IPv4 and 1 IPv6 address.
And then there was a problem in receiving ports on the VDS.
Under the contract, a range of IPv4 NAT ports 100-120 was provided.
SSH is up and running and works great. Apache on IPv6 is given, as in other matters and everything else.
But here's the problem. I can not figure out how to organize the reception of ports on IPv4 within the provided range.
For example, the organization of reception of 80 and 443 ports.
SolusVM control panel. NatVPS service provider (Hostrails).
Maybe someone faced this problem?