Kubernetes Traefik internal server error on every other request
I saw in the traefik logs that HTTP connections are fine but when HTTPS redirections happen for favicon etc. then you get x509 sertificate not valid. That's because wordpress pod has ssl certificate that's not valid.
You can use --serversTransport.insecureSkipVerify=true safely inside your cluster since traffic will be encrypted and outside traffic is HTTP.
If you need to use trusted certificate in future, deploy it with wordpress app and use traefik with ssl passthrough so traffic would be decrypted at pod level. Then you can remove insecure option on traefik.
I'm not really sure why and I can't explain it but when I add this option the random failures stop:
--serversTransport.insecureSkipVerify=true