I have gitlab running on a server in a private network. There is also a client host.
When running an “empty” shell runner on a client host, an ssl error occurs. Here is the runner log:

Running with gitlab-runner 15.1.0 (76984217)
on test ePB5977y
Preparing the “shell” executor 00:00
Using shell executor…
Preparing environment 00:00
Running on develop.gobus.online…
Getting source from Git repository 00:01
Fetching changes with git depth set to 20…
Reinitialized existing Git repository in /home/gitlab-runner/builds/ePB5977y/0/gobus/gobus/.git/
fatal: unable to access ‘https://gitlab-ci-token:[MASKED]@gitlab.gobus.online/gobus/gobus.git/’: server certificate verification failed. CAfile: /home/gitlab-runner/builds/ePB5977y/0/gobus/gobus.tmp/CI_SERVER_TLS_CA_FILE CRLfile: none
Cleaning up project directory and file based variables 00:00
ERROR: Job failed: exit status 1

The gitlab.gobus.online certificate is valid.
What could be the reason?