One place I’ve run into these kinds of errors frequently was in a heavily locked down corporate LAN. All kinds of messed up firewall rules doing wild things. As

One place I’ve run into these kinds of errors frequently was in a heavily locked down corporate LAN. All kinds of messed up firewall rules doing wild things. As an example, had a node with a misconfigured egress rule. Trying to connect to it, the node would receive the SYN, but the SYN/ACK would get eaten on egress... so for 60 seconds both sides believed a connection existed, but you couldn’t do anything. Then it times out and starts all over again.