create the file:
/containers/traefik/configuration/certificates.toml
with content:
[[tls.certificates]]
certFile = "/certs/traefik-krai-be.crt"
keyFile = "/certs/traefik-krai-be.key"
[[tls.certificates]]
certFile = "/certs/portainer-krai-be.crt"
keyFile = "/certs/portainer-krai-be.key"