Task and Management tools for isolated networks

Hey all! I need your help and consultation on project management tools.

My company is pretty out dated in tracking progress in development, so I’m looking for the best and easiest tool to integrate into our development process. We develop software and I am looking for a tool that can help team leaders track progress as well as help our POs and PMs communicate better with the team leaders.

I’d rather it to be web-based, however I do have to mention that we work on an isolated network and access to the internet is not always available so if there is no dedicated server option I will prefer a desktop application.

I don’t really care about integration with a lot of other platforms, however integration git/gitlab is a pretty big plus, and integration with confluence and outlook will be nice too but hardly a deal breaker.

Any help with that? Thanks!