Advantech Devops Engineer interview questions

There were 3 interviews: recruiter, technical, online 200 questions personality test, and the introduction of the company in the office. At the end of the last interview in the office, I was offered 20% lower salary, than I communicated in the first round. After I have shown interest in company's products inside the office, and the readiness to do the job and invested 4 hours, I got an offer 20% below my communicated expectation, so I refused it.