Recognizing that different cultures have different norms I'm going to be brave and say I recognize some jealousy here.
I say brave because the problem with mentoring is our answers are only as good as your description of the problem. I am also making some assumptions here. I'm assuming he doesn't contribute to income(not an issue in itself as he does the home making). Im assuming you own/rent a home together and live together.
There is an example you give in your back-story that stands out.
He doesn't spend his free time with technical issues anymore. Any time something around his pc, our home network, the router or peripheral devices etc. is broken, he expects me to fix it because 'I am the master of technology' and kind of mocks me, when I'm not able to.
If this started around the time you graduated and or landed your new job that might indicate some jealousy on his part. The mocking part might just be his way of leveling the field a little
"Yes you have your degree but your not that much better than me".
A simple response to this might be "Well your the one asking me! You broke it!"
You haven't indicated what he did before he became unemployed or why, What his aspirations were/are, What his education/experience is and what he has done about it in response so it is difficult to relate and offer up past experience where possible. Finding out what he plans to do in order to contribute when the little one starts school will be a good measure of his mind set.
Your direct question "How could I make him stop ruining my free evenings?" could be rephrased slightly and instead answer the question "How can I find a way to relax that agrees with both of our requirements." This is going to be a team effort and will need buy-in from both of you.
As for how to talk to him, A quick fix that worked for me was to stick some wellies on the little one and take down-time outside and away from any distractions. A walk or kick around worked quite well. This should help give time to workout what to do at home, if nothing it helps lubricate conversation a little.
This will only work if your husband is not glued to his pc and reluctant to have any time away from it. You have not said what he does with it. Is he studying? Is he researching? Does he freelance? Does he contribute to the households cash flow in any way? Does he intend to soon and he's building his way there?. If he is simply "Fiddling" you could recognize that too him but also understand that might be his way of unwinding too.
Being a parent is hard work, You mention daycare and I am assuming this is stay and play where he stays with little one with out much chance for a break. One question to ask would be what he intends to do when the little one starts full time school? As this will significantly shift the pressure onto you, And most likely cause resentment on your side.
Some suggestion's then to start with might be:
Decide and work out if he is at all jealous in any way. What he is jealous of and how that manifests might be two different things. This is best done with indirect questions, perhaps even a story. If you suspect he is jealous of your degree then a story of how a friend you studied with that dropped out of uni has just landed a job as a junior programmer and is doing well, might just illicit a response. See what his response is and go from there. Obviously keep it factual and relate-able. How you deal with where to go next is another Question all together.
What does he do on his pc that requires so much attention from you? Could your intervention to fix something not wait a day or two while you have a "Date Night" or "Quiet Night". If he has the technical knowledge but would rather see the 'Qualified' one do it in order to 'Justify' or 'Prove' your time at uni then that again is a whole other Question.
Find some common but neutral interests if you want to unwind together.
If all else fails the blunt approach usually works, a good fall out usually clears the air in my experience.