We have seen a lot of unavailability on lichess this week. I'm facing a server configuration issues that gives me sleepless nights.
For those who care, I'm getting TCP SYN flood warnings in the kernel logs. I've tried many configurations tweaks using sysctl without much success: The site keeps getting down after around 1 hour of
activity, depending on the number of players online.
I'm now trying to tweak (read = hack) the java application server (netty) to increase its receive buffer stack size and backlog.
Until the right fix is found, we endure episodic failures, generally characterized by the infamous "Error 500" screen.
Sorry for the inconvenience, I hate it as much as you do. I'm working on it.