I managed to somehowe partial resolved this issue.
When dlna stops indexing I opened dnla server in windows media player. I added coloumn where I saw all names added in dlna with prefix 1,2,3,4,...
So it was easy to find on which file indexing stops. I remove next file and indexing continued. I needed to remove several files, I don't know yet what those files are different from others.
I hope this will be helpful.