Fortinet Embedded Software Developer interview questions

I applied a different position but called for interview for embedded software engineer. I passed their home test (2.5hr) and then were called on for an onsite interview. I think they just use the home test to verify if you can write code, nothing more than that. In the email, it was mentioned I should check their products and get familiar with network techniques. I spent a few days on that. On the onsite interview, there is actually 1.5 hr coding test, with a couple of coding questions. There was nothing tricky in their coding test , all basic textbook algorithms (sorting, searching, linked list,.., pointer manipulation) but definitely needed muscle memory. I was told my background was not a good fit at the very beginning of the interview. Then I got frustrated and performed pretty poorly during the interview process.