You need to associate a drive letter to the network path you want to use. To do this, execute the following command in the Windows cmd shell:
pushd \\servername\share\path\to\folder
The next prompt will carry the assigned drive letter, e.g. Z:\path\to\folder. Now, open Git Bash (it will not work with an already running instance) and go to the new created drive letter:
No need to type the path manually. Just right click! on your repository and click Git Bash option.
It will open the git bash with your repository path.
Also i suggest to use Mp Network Drive option of windows to map the network location as a drive and use it only.