
Frustration at its best!
I am a .Net developer, I have long long experience with technologies in general, but it look like companies only are interested in younger people, 28 and less years old, I'm 43. It is incredible the frustration that I have when the interviewer has no knowledge of technology, and still they "some how" got in a position that is key for a company. I applied in others companies where the oldest person there is probably 25. What's wrong here? Is that mean that after you turn 35 you need to retired? It is amazing!

They want younger so they pay chipper.

I agree with you ,it does seem to be that way.

Although ageism is a real and rampant discriminatory practice, I doubt that age alone is the barrier. You tell us that you're a .NET (not .Net) developer. For how long? You also mention "long long experience with technologies in general". I'll take your for it, but I'd like to know which technologies. By the way, experience is good, but how proficient are you? I don't know but I've been told that software developers are always under harsh deadlines.
I can empathize with having to educate some non-technical interviewer. I'd rather speak with the real hiring manager, and he or she better be technically-trained! And there's no excuse for that, as more universities offer majors in technical management. Also, although it is commendable when a small number of hyper-talented young people come together and incorporate a startup business, it is best to let them mature out of their conceits and youthful exuberance; as at 25 years of age, they still think they're "the cock o' the north". There are more than enough long-established integrated technologies and software laboratories where you can find a home for your talents.
Finally, brush up on your English grammar. This is because hiring managers interpret good control of grammar as good control of coding. Stay strong.

Try to get into the latest tech. Angular/Web API. All the best. I am 46 and i am in these tech and found a job easily. Pure .NET might be difficult

I know how you feel Luis. I'm the same age and I get passed over quite a lot. Even temp agencies appear to have given up.

The world is amazing

Life is not the way it's suppose to be, it's the way it is. The way you cope with it is what makes the difference, There are a few opportunities, out there, where you can be self-employed and work from home during the work you are train to do, and they pay a very good hourly wage, they are called freelancers.

I work for a full stack software development company in Dallas. While a majority of our devs are in their twenties, they are often interns who get paid less. The downside is, they are wholly inexperienced and take longer on projects with a lot of code reviews and re-writes as a result of said inexperience. You get what you pay for.
We do have our fair share of older devs too, but they find the young culture offputting. I am 43 years old and an IT business analyst. I am the fourth oldest employee in the company if that gives you any indication of the industry as a whole.
We also do not exclude anyone based on age. If you can develop and can work in an autonomous but loud/busy environment, and buy into the culture of the organization, then you will get hired, get paid well, and be able to stick around as long as you want.
Too bad you don't live in Dallas, Texas, we are currently hiring for a .NET developer.

May this new year you get loads of better opportunities!! All the best