Dedicated certificate for Gitlab Page

I am trying to get GitLab Pages for GitLab CE installed on my own server to serve a letsencrypt certificate for that specific page, but page.otherdomain.de still serves the certificate for gitlab.domain.org.

Settings in gitlab.rb:

external_url "https://gitlab.domain.org"

nginx['redirect_http_to_https'] = true
nginx['ssl_ciphers'] = "ECDHE-ECDSA-AES256-GCM-SHA384:…"
nginx['ssl_prefer_server_ciphers'] = "on"
nginx['ssl_protocols'] = "TLSv1 TLSv1.1 TLSv1.2"
nginx['ssl_session_timeout'] = "1d"
nginx['ssl_dhparam'] = "/etc/gitlab/ssl/dhparam.pem"
nginx['add_header'] = "Strict-Transport-Security max-age=15768000"
nginx['ssl_stapling'] = "on"
nginx['ssl_stapling_verify'] = "on"

pages_external_url "https://otherdomain.de"
gitlab_pages['enable'] = true
pages_nginx['enable'] = true
pages_nginx['redirect_http_to_https'] = true
pages_nginx['ssl_certificate'] = "/etc/gitlab/ssl/#{node['fqdn']}.crt"
pages_nginx['ssl_certificate_key'] = "/etc/gitlab/ssl/#{node['fqdn']}.key"
pages_nginx['ssl_ciphers'] = "ECDHE-ECDSA-AES256-GCM-SHA384:…"
pages_nginx['ssl_prefer_server_ciphers'] = "on"   
pages_nginx['ssl_protocols'] = "TLSv1 TLSv1.1 TLSv1.2"
pages_nginx['ssl_session_timeout'] = "1d" 
pages_nginx['ssl_dhparam'] = "/etc/gitlab/ssl/dhparam.pem"
pages_nginx['add_header'] = "Strict-Transport-Security max-age=15768000"

Symlinked certificate files:

root@srv:~# ls -la /etc/gitlab/ssl/
dhparam.pem -> /root/letsencrypt/dhparam.pem
gitlab.domain.org.crt -> /etc/letsencrypt/live/gitlab.domain.org/fullchain.pem
gitlab.domain.org.key -> /etc/letsencrypt/live/gitlab.domain.org/privkey.pem
otherdomain.de.crt -> /etc/letsencrypt/live/page.otherdomain.de/fullchain.pem
otherdomain.de.key -> /etc/letsencrypt/live/page.otherdomain.de/privkey.pem
page.otherdomain.de.crt -> /etc/letsencrypt/live/page.otherdomain.de/fullchain.pem
page.otherdomain.de.key -> /etc/letsencrypt/live/page.otherdomain.de/privkey.pem

I symlinked both otherdomain.de and page.otherdomain.de as I was not sure which was the way to go, but neither solution seems to work.

Any suggestions what could be the problem?

when those settings are commented, it works as expected:

#pages_nginx['ssl_certificate'] = "/etc/gitlab/ssl/#{node['fqdn']}.crt"
#pages_nginx['ssl_certificate_key'] = "/etc/gitlab/ssl/#{node['fqdn']}.key"