Outputs:
    VPCId:
        Description: VPC ID
        Value:
          Ref: VPC
        Export:
          Name:
            Fn::Sub: "${AWS::StackName}-VPCID" # <-----------------

Parameters:
  NetworkStackName:
    Description: Name of the base stack with all infra resources
    Type: String
    Default: BaseStack # <------- ${AWS::StackName} from the other Cloudformation template
    
Resources:
  WebServerInstance:
    Type: AWS::EC2::Instance
    Properties:
      InstanceType: t2.micro
      ImageId:
   - SOMETHING FROM MY REGION
      NetworkInterfaces:
      - GroupSet:
        - Fn::ImportValue:
            Fn::Sub: "${NetworkStackName}-SecurityGroupID" # <---------------