Over the weekend, our instances have started being marked as unhealthy, and not being enabled within the load balancer.
When going to the public DNS of the instance, followed by the healthcheck.html file, I instantly receive a 200 OK response, but ELB doesn't recognise this. Our settings haven't changed for weeks, yet this has just started happening.
I have tried deregistering the instance and adding it back in again, but with no success.
Does anyone know if this is a known issue, or if something has changed on the backend? The healthcheck file doesn't return a body, but this hasn't been an issue before.