an authentic Lithuanian yeshiva

Therefore I should explain what yeshiva was when it was idealistic. The basic idea was you would sit and learn Talmud from about 18 years old until some father of a daughter would come into the yeshiva and ask the rosh yeshiva [teacher] who would be a good match for his daughter. Then 6 dates would be set up between the two on Saturday night. After 6 dates  an announcement was made.
After the marriage the son in law would be supported by his parents and then her parents alternatively.
He would continue to learn Torah.
The community would be surrounding the yeshiva and it would be isolated from the outside would by invisible barriers, mental barriers,- rules that were eagerly accepted and loved. The rules were voluntarily accepted by all and followed by all. The rules were the Torah-the oral and written law of God. And the ideal was to learn Torah all one's life. Learning Torah was the life goal.

After some years the young man would begin to work at some job.

What happened to change all this? Success.  When an organization is successful and there is money and power, then the people at the top tend to be the most materialist in direct opposition to the kinds of people that started the whole thing. Greed and corruption got to be the norm. It is like the Olympic committee that gets all the perks. The country that hosts it looses money. So Norway simply turned down the opportunity to host the Olympics.

Though in its pristine form the system should work well. It did not for me. So I am hesitant to recommend a return to it. For me no one helped find my wife. She came running to NY to get me. The only thing people at the top did was to try to ruin my marriage when they got the chance.
So the yeshiva world certainly has gone down in quality. Thus my present day recommendation is the Beit Midrash--an informal place to learn Talmud with no official aspects at all. Simply a place for learning Gemara for whom so ever wishes to learn Gemara. I was hoping to do this on my own but that did not work very well. I can not seem to even make my own small a place into a place of Torah. Still I can hope to encourage others.
That is all I am saying is this. Even if the whole world has turned  Torah into a business, still one can by himself learn Torah for its own sake.

[What I am saying here is a lot really depends on your own situation. If you have an authentic Lithuanian yeshiva in your area that as far as you can tell are learning Torah for its own sake and not for money then by all means join in. But if there is nothing like that are perhaps the places that are near you seems to be either all about using Torah to make money or perhaps are insane asylums as many yeshivas are, then it is best to learn Torah at home. Learning at home should at least in theory be easy. All you need is a Gemara  and a book of Musar.]