Connection fails on first request after some time with no activity

I’ve started having issues with API requests failing on the first call after a longer period of inactivity. For example if 10 min or so passes without any calls to the server, the first call after this period will fail. If I immediately resend the request, the second call will succeed. So it almost seems like something falls asleep and wakes up on the first call, but somehow does not manage to handle that first request.

I have setup a simple ping endpoint that responds with a pong. But on this first request, there is no response, no error code, no trace in the logs. It does not even seem like the request reaches the server at all. I don’t believe this issue has always been here, so it might be something new. Is something failing on fly’s side before the request reaches the server?

Endpoint service: