Hi! I just encountered this issue and the root cause was the readiness and liveness probes checking /ping on the traefik port. Basically what the error message means is, that those listening sockets have been externally closed, in my case due to the pod being terminated because it did not become ready.
The actual root cause was related to this:
where the most important point is, that mixing cli and yaml configuration will not work, as yaml will always supersede the command line flags
Hope this helps someone.