Relay.infosec.exchange has been a bit unreliable lately - recent versions of the AodeRelay software appear to have a memory leak that causes the process to terminate. I just applied the latest update and configured systemd to restart the service if it gets killed.
The other issue is that the relay is getting quite busy. It's running on a 6 core/12 thread bare metal server with 64gb of memory and (when its working) the CPUs are close to pegged. I will look at upgrading to a larger server soon. Apologies.