After number or requests no communication with the server

I try a loop to get officers data. But after some requests there is no communication with the server.
I get a 443 error because I have a timeout setting. I don’t even go near the rate limit. I am talking about 100 iterations or so. It not a specific company that causes it, neither there’s a pattern.
It stops getting responses randomly.
It’s just as if you’re not allowed to request many companies (many<100) in a short time.
Is there any other limit besides the 600 requests/5 mins?