Describe your question in as much detail as possible:
We are making use of GitLab Community Edition 15.10. We are trying to integrate a client’s Jira account to some of the projects/groups on our gitlab.
I’ve tried to integrate it from Jira side. So when i choose the self managed gitlab option on Jira, I enter the URL and it says “Failed to update the GitLab instance. See the troubleshooting documentation.”
Hopefully noone with power has insisted that we do that yet (our Jira lives in the cloud (and as far as I have understood that is all atlassian sells these days), and our GitLab is too well protected), but because people have asked about it I have read up on it. So if you have a setup where it’s possible (or are ready to make one), it sounds easy.
I suggest to check the troubleshooting guide. Usually, the problem is that GitLab instance is not reachable from Atlassian, but check all the mentioned prerequisites in the docs.
I have a feeling it’s firewall issue.
Is there a possibility you can try connecting some other jira to it just to see if it connects? if it doesn’t then the issue is on gitlab side, if it does then issue is with jira cloud (which is unlikely).
try stopping firewalld, iptables and disable selinux (as a test) and try connecting, then enable back