Trellis - SSH [UNREACHABLE! => {"changed": false, "unreachable": true}] Error

Dear @swalkinshaw, I did created the full new droplet and started the whole process again 2-3 times.

I successfully did deployed the trellis by using the github public repo, but when I use gitlab repo then that time it give me error

---------------------------------------------------
Git repo git@gitlabrepo/wordpress-starter.git cannot be accessed. Please
verify the repository exists and you have SSH forwarding set up correctly.
More info:
> https://roots.io/trellis/docs/deploys/#ssh-keys
> https://roots.io/trellis/docs/ssh-keys/#cloning-remote-repo-using-ssh-
agent-forwarding

fatal: [serverip]: FAILED! => {"changed": false, "failed": true}
	to retry, use: --limit @deploy.retry

PLAY RECAP *************************************************************************************************************************************************************
serverip              : ok=7    changed=0    unreachable=0    failed=1   
localhost                  : ok=0    changed=0    unreachable=0    failed=0   

I did checked my ssh ForwardAgent and droplets AllowForwardAgent, all are working fine, in local, vagrant and droplet setup.

I checked multiple threads, and see that this kind of issue has been faced by many, but their solution didn’t worked for me.

Can you please tell me if I’m missing any key points.