PhD Mathematics, University of Hagen I am 30 and work for an IT company in Germany as a software developer.

I did B.Sc. in Mathematics (pure) and M.Sc. in Computer Science. Since then I've occasionally spent time with solving math problems or learning new topics.

I've long been dreaming of doing a PhD in Mathematics and I'm especially interested in the Analysis.

If I had financial freedom I would've started a full-time PhD right now but it's not possible, since I'm financially responsible for my own family and for my parents.

At my current job I have a 6-hour schedule, which means that I'd have about 3 hours in the morning and about 2-3 hours in the evening to work on my dissertation. On the weekends I'd be able to give another 10 hours combined. So this makes about ~35 hours per week that I can carve out.

In Germany there is a public (and the largest) University of Hagen, which offers onsite and remote education. It specifically focuses on people, who might not have the possibility to be onsite. It is about 2h of driving from me, so I'd be able to go there from time to time.

Has anyone had experience with that University and what you think of the feasibility of my plan? I understand that it'd be impossible to finish the studies in a regular time of 3 years. I'm talking more of 5-6 years of work.

Almost forgot to mention. I'm also willing to spend about 3 hours / day while in vacation or on holidays with no exceptions.

Another thing that I thought of is going with the dissertation while saving some money in that time and then taking a leave of absence at work for about 1 year while surviving on that money (maybe even combining it with a scholarship if that is possible). 

So if it goes well, I'd definitely accelerate in the end by switching to full-time for 1 year and finalizing the work.
Talk to them, the advisors will have met people with all options / constraints...

Or go and see them...