SpringBootAdmin configuration behind SpringCloudGateway

Question

My Spring-Boot-Admin-service is running in a docker-container behind a Spring-Gateway. For this I configured the public-url this way:

spring:
  boot:
    admin:
      ui:
        public-url: "https://myAppname.intranet.cnb/monitoring/"

My problem now is, that spring-admin by default adds a port (in my case "8080"), if it is omitted. This results in a URL

https://myAppname.intranet.cnb:8080/monitoring/

A port in this public-url does not work for me. Any idea how to configure this public-url without a port?

Thanks!