Cannot push/pull GitLab when ssh from other machine

I have a machine setup for development, I can push/pull from GitLab locally. When I connect to that machine via SSH (terminal or vs code), all the actions failed with "Permission denied (publickey)."
what was the problem and how do I fix it?
thanks.

I have checked the SSH Keys under User Settings, keys from both machines (the development machine and the one SSH from) are valid.

as suggest by @Martheen

> the output of ssh git@gitlab.com -T -vvv

then the local finished to test and the ssh one failed.

> in ~/.ssh are openssh private and public keys some_name and some_name.pub, dont have any keys with default names (id_rsa, id_dsa, id_ecdsa, id_ed25519), thus the (nil) in the log.

That means, if any push/SSH connection is successful (with non-standard named keys), you should have a ~/.ssh/config file.

Check its content for something like:

Host gh
  Hostname gitlab.com
  User git
  IdentityFile ~/.ssh/some_name

If you do have such an entry, check the output of ssh -Tv gh: it should authenticate you with the right user.

Use the Git remote URL gh:me/myrepo.

> How the git with ssh use the key and why it work locally without the config files?

• The Git with SSH will use the right key if the git remote origin used for that repository is gh:me/myrepo (not git@gitlab.com:my/myrepo)
• it is working locally if your keys have the standard name, or if you also have a ~/.ssh/config file.