Finding a 4 days/month job on top of my full-time job

The company I work for would be a great fit -- we specialize in conducting remote technical interviews as a service. It pays pretty well ($100 USD per 90-minute interview, slightly higher as you become experienced on the platform). The work is very flexible and you set your own hours, so it works for people aiming for a lower volume per month such as yourself, as well as people interested in more than that. We have some folks who work full time on our platform, and some who only do 3-4 interviews per month.

Particularly if you have the skillset for mentoring, it's likely this would be a great fit for you.

If this is the kind of thing you (or anyone else reading this) might be interested in, send me an email and I would be happy to talk further about it! My email address is in my profile.

Look for small businesses that need dev capacity but can't afford full time people/and do not need them. They often post on Indeed looking for someone dirt cheap per hour, but you can pitch them on part time work at a higher rate, but because you are more experienced and skilled (presumably), you can make the case that it will cost the same.

I have done this successfully twice.

> I found a job for mentoring students (1h X 4 times a week). I find it hard because I have to keep an eye on 2 or 3 different students.

In a similar position, I found one-to-one tutoring to be a much better idea. This means you can focus on one person, but also means you can charge much more as you build up demand.

I can see you finding a job that just requires to get stuff done, so working in your own time and spreading it out, would take about 243 = 72 or 244 = 96 hours to complete. These type of consulting jobs are available all over the place. Maybe look at upwork and fiverr?

Plenty of opportunities out there. Reach out to companies that are working on things you have expertise in and contracting shops.