For those trying to host a git server on your home network like I have and encountered network issues even after port forwarding, you might be behind carrier grade NAT.

You'll need some forwarding solution, or use an SSH reverse tunnel to punch through CGNat.

Use something like ngrok or localhost.run. For example if you're using gitea, host it on localhost:8080 then run this:

ssh -R 80:localhost:8080 localhost.run

This will forward localhost:8080 to <subdomain>.localhost.run

Now you just pass <subdomain>.localhost.run to colleagues and they'd be able to connect to your self-hosted git instance.

Now do the same for ssh port.

Caveat that your traffic would route through localhost.run, so it's best to not use this for anything serious, or alternatively host your own reverse SSH tunnel on a VPS somewhere.