Without tying it directly to the load balancer, but you can add a backend service consisting of an automatically scalable group of instances located in the Google cloud that will proxy incoming traffic to an external server. This will result in overhead for billing and maintaining such an auto-scalable group of instances. Therefore, depending on the amount of traffic that you process, another approach may be to route traffic through an existing backend service, that is, configure servers running in your existing server service by adding the appropriate conditions (route routing, etc.) And the proxy to the external server instead relies on the HTTP HTTP Balancer to complete the route-based routing part.