It's really quite variable, most of our clients are pretty good, ranging from frighteningly competent (a large well-known test equipment manufacturer) through to reasonably OK but maybe a bit out of their depth and in need of some advice, so these guys were really the exception. Having said that our stuff is highly tuned towards making it easy to use/minimising our tech support load, so most of what comes in is intelligent questions where it's not a chore to answer them.
Yeah, the 80%/20%, or one fifth, isn't precise at all, it's the idea how effort and results seem to correlate whenever humans are involved.
In your case, it just means that it is
normal to have a small fraction of clients that consume a relatively large fraction of support resources. It sounds like you monitored the issue and dealt with it effectively, and I do applaud that –– and I would even if I myself were that client.
My point is, such cases are to be expected because of humans, regardless of how good your documentation and non-human-interactive support is.
Those who are not aware of the Pareto effect, may think that because they have a few such users, their documentation etc. is insufficient; but it may just be human nature instead. Similarly, those who only listen to clients who contact support, should remember that just because the clients ask for something, it may not be what they need or even want.
With regards to open source software, most people do not
grok that the free/open refers to
libre, not
zero cost. (I am not referring to OP here, but to humans using open source tools in general.)
Free/open source software definitely evolves in a market of sorts, and you don't get support –– or anything, really, except for a copy of the software itself –– for no cost. It is just that typically, the cost is paid in time and effort by knowledgeable people, instead of money. This means that to get support with LwIP, MbedTLS, etc., you need to have contacts with such people, and have some way of convincing them to help you. Smallish sums of cash money are often considered more a nuisance than help, because the knowledgeable ones tend to already have well-paying jobs, and an exchange of money only makes things more complicated (especially the direct relationship, expectations, timetables –– contracts, really). So, even if you do have a reasonable budget, it is definitely not straightforward at all.
The end result is that people like OP find it very difficult to obtain support, because we haven't yet discovered the business models that can bridge things here in a mutually beneficial manner.
In fact, based on what I know about the business side (used to run an IT company myself for a few years around the turn of the century; did well, but it burned me out mentally) and about the FOSS world, I suspect such business models have to be based on nonprofit model. I do not like the direction companies like RedHat (owned by IBM) or Canonical (Ubuntu) are taking their development and support, but Linux Foundation, Apache Software Foundation, Free Software Foundation, and other nonprofits in this area seem to work.
I'm guessing what OP and others' really need, is a credible foundation-type nonprofit, that provides access to knowledgeable developers for support on basically any FOSS project; roving problem-solvers and bug-hunters, if you will. You don't actually pay the developers directly, but support the foundation, which in turn supports the developers. Since the developers do not work for the people asking for support, but for the foundation, there are ways to resolve the "not very competent client demanding excessive support" problem, which a direct relationship does not allow (except by dropping the client).
Problem is, the developers and learners who'd love to be part of that even part-time, and the business/admin people (with enough spine to not actually exploit the structure for their own personal financial benefit) who could run such an organization, just do not meet in the current world.
Or perhaps I am utterly wrong, as I sometimes am.