How to advance as a .NET developer?

Hi /dotnet family. I’m a junior .NET developer and just started working at an awesome company. I would say 50% of my knowledge is frontend and the other 50% is backend. I like both ways of programming but I have been asked to work on frontend stuff a while for a client. As a junior I don’t want to say no to a project and I have told them I want to work with backend stuff later.Until then I want to advance as a .NET developer too and learn more when I have spare time. I’m afraid I will lose knowledge if I don’t. The best way to learn is ofcourse to work on real projects, but that’s not an option for now. So I’m asking for advice how to become better on my own? I need hints on real life scenarios for things I can build.Two things I know I need to improve is Authentication and working with files(e.g. extracting data from a large Excel file).Thanks via /r/dotnet https://ift.tt/2H4Jytw