Upgrade from 10.7.4 strange behaviour - external acess wrong URLs (internal instead external)

I have one instance of sameersbn/gitlab:10.7.4 running.
I access it from external through an apache reverse proxy. This works fine.
Until I had the idea to use a new version of gitlab .
I I create a new container with my existing docker-compose.yml the instance works.
But if I access it from my ddns-domain (homeserver.mydonain.com/gitlab/ )through the reverse proxy the URLs to the files in the projects are the internal Urls (localserver:10081/gitlab/ ).
What has been changed in the configuration?
Has I been to optimistic that I just changed the image-version?
`version: '2'

services:
redis:
restart: always
image: sameersbn/redis:latest
command:
- --loglevel warning
volumes:
- /ssd/docker/sameerdbn-gitlab/redis:/var/lib/redis:Z

postgresql:
restart: always
image: sameersbn/postgresql:latest
volumes:
- /ssd/docker/sameerdbn-gitlab/postgresql:/var/lib/postgresql:Z
environment:
- DB_USER=gitlab
- DB_PASS=password
- DB_NAME=gitlabhq_production
- DB_EXTENSION=pg_trgm

gitlab:
restart: always
image: sameersbn/gitlab:latest

image: sameersbn/gitlab:10.7.4

depends_on:
- redis
- postgresql
ports:
- "10081:80"
- "10023:22"
volumes:
- /ssd/docker/sameerdbn-gitlab/gitlab:/home/git/data:Z
environment:
- DEBUG=false

- DB_ADAPTER=postgresql
- DB_HOST=postgresql
- DB_PORT=5432
- DB_USER=gitlab
- DB_PASS=password
- DB_NAME=gitlabhq_production

- REDIS_HOST=redis
- REDIS_PORT=6379

- TZ=Europa/Vienna
- GITLAB_TIMEZONE=Vienna

- GITLAB_HTTPS=false
- SSL_SELF_SIGNED=false

- GITLAB_HOST=bigserver
- GITLAB_PORT=10080
- GITLAB_SSH_PORT=10022
- GITLAB_RELATIVE_URL_ROOT=/gitlab
- GITLAB_SECRETS_DB_KEY_BASE=<here is my key>
- GITLAB_SECRETS_SECRET_KEY_BASE=<here is my db key base>
- GITLAB_SECRETS_OTP_KEY_BASE=<here is my optkey base>

`

Start with the docker-compose.yml environment for the GitLab container, especially GITLAB_HOST, GITLAB_PORT, and GITLAB_RELATIVE_URL_ROOT, then inspect the Apache reverse-proxy configuration described in the report. Reproduce the upgraded container through the external /gitlab/ URL and compare generated project-file links with version 10.7.4; done means external links no longer expose localserver:10081.