> Some routers and firewall silently kill idle TCP connections without telling application. Some code (like HTTP client libraries, database clients) keep a pool

> Some routers and firewall silently kill idle TCP connections without telling application. Some code (like HTTP client libraries, database clients) keep a pool of TCP connections for reuse, which can be silently invalidated. To solve it you can configure system TCP keepalive. For HTTP you can use Connection: keep-alive Keep-Alive: timeout=30, max=1000 header. Once a TCP connection has been established there is no state on routers in between the 2 ends of the connection. The issue here is firewalls / NAT entries timing out. And indeed, no RSTs are sent. We had the issue in K8s with the conntrack module set too low. Now, you can try to put in an HTTP Keep-Alive, but that will not help you. The HTTP Keep-Alive is merely for connection re-use at the HTTP level, i.e. it doesn't close the connection: https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Keep-Alive https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/... An HTTP Keep-Alive does not generate any packages, it merely postpones the close. A TCP Keep-Alive generates packages which resets the timers.