BigPay Backend Developer interview questions

Big pay has a interesting recruitment process which they initially gather all the candidates into 1 big meeting room and have a round table discussion with the company technical founders. It gives me the initial impression of a very open culture. After that I got a relatively hard coding test which is sort of an open-end test which I don't think it's fair to elaborate too much due to fairness. The interview process was a bit of let-down for me though as interviewer seems to be more keen to test me on how I troubleshoot a zero-byte socket connection due to his xp instead of spending more time on how solve the coding challenge. In general, I felt that they were polite but not friendly.