This is possibly unrelated directly to the question; but one mistake I just made myself, and I see in the OP, is the URL specification ssh://user@server:/GitRepos/myproject.git - namely, you have both a colon :, and a forward slash / after it signifying an absolute path.

I then found Git clone, ssh: Could not resolve hostname – git , development – Nicolas Kuttler (as that was the error I was getting, on git version 1.7.9.5), noting:

The problem with the command I used initially was that I tried to use an scp-like syntax.

... which was also my problem! So basically in git with ssh, you either use

ssh://username@host.xz/absolute/path/to/repo.git/ - just a forward slash for absolute path on server
username@host.xz:relative/path/to/repo.git/ - just a colon (it mustn't have the ssh:// for relative path on server (relative to home dir of username on server machine)
Hope this helps someone,
Cheers!