@<1523701087100473344:profile|SuccessfulKoala55> Thank your for your advice. I have updated the clearml agent version to 1.7, cleared the cached and forced the server port (it wasn't 22) and also forced the ssh user to git. The error has changed slightly:

cloning: 

_company.com:1234/our_gitlab/our_repo.git
Using SSH credentials - ssh url '

_company.com:1234/our_gitlab/our_repo.git' with ssh url '

_company.com:1234/our_gitlab/our_repo.git'
git@our_tools.our_company.com: Permission denied (publickey).
fatal: Could not read from remote repository.
Please make sure you have the correct access rights and the repository exists.
Repository cloning failed: Command '['clone', '

_company.com:1234/our_gitlab/our_repo.git', '/home/ec2-user/.clearml/vcs-cache/our_repo.git.c3e87922dd57630bb815feb7dcb4354b/our_repo.git', '--recursive', '--quiet']' returned non-zero exit status 128.
clearml_agent: ERROR: Failed cloning repository. 
1) Make sure you pushed the requested commit:
(repository='

_company.com:1234/our_gitlab/our_repo.git', branch='main', commit_id='f6d54eadf0108a3af243595426a710c150e14861', tag='', docker_cmd=None, entry_point='lstm_training.py', working_dir='tasks')
2) Check if remote-worker has valid credentials [see worker configuration file]

I tried to force the host, but it didn't work - for some reason it started using the agent instance user (ec2-user) instead of git.

Could it be due to the fact that our gitlab instance isn't hosted on our_tools.our_company.com:1234 but on our_tools.our_company.com:1234/our_gitlab/ ?