K3s traefik and let's encrypt: Cannot get certificates up and running

I've been reading past examples and still cannot find out what it is that I'm not figuring out.

      - args:
        - --global.checknewversion
        - --global.sendanonymoususage
        - --entryPoints.traefik.address=:9000
        - --entryPoints.web.address=:8000
        - --entryPoints.websecure.address=:8443
        - --api.dashboard=true
        - --ping=true
        - --providers.kubernetescrd
        - --providers.kubernetesingress
        - --accesslog
        - --log.level=DEBUG
        - --certificatesresolvers.myresolver.acme.tlschallenge
        - --certificatesresolvers.myresolver.acme.email=<mel@evilcorp.com>
        - --certificatesresolvers.myresolver.acme.storage=/data/acme.json
        image: traefik:2.2.1

And in the logs, I see

time="2020-05-23T15:50:15Z" level=debug msg="legolog: [INFO] Unable to deactivate the authorization: https://acme-v02.api.lets
time="2020-05-23T15:50:15Z" level=error msg="Unable to obtain ACME certificate for domains \"erdos-labs.xyz\": unable to generate a certificate for the domains [erdos-labs.xyz]: error: one or more domains had a problem:\n[erdos-labs.xyz] acme: error: 400 :: urn:ietf:params:acme:error:connection :: Connection refused, url: \n" providerName=myresolver.acme routerName=default-omnio-server-tls-8f58c17c54e0549fcb31@kubernetescrd rule="Host(`erdos-labs.xyz`)"

I've checked that the address is reachable on port 443, by doing a telnet. And the challenge says that the domain was resolved:

  "identifier": {
    "type": "dns",
    "value": "erdos-labs.xyz"
  "status": "invalid",
  "expires": "2020-05-30T15:50:10Z",
  "challenges": [
      "type": "tls-alpn-01",
      "status": "invalid",
      "error": {
        "type": "urn:ietf:params:acme:error:connection",
        "detail": "Connection refused",
        "status": 400
      "url": "https://acme-v02.api.letsencrypt.org/acme/chall-v3/4765642639/8c4C2w",
      "token": "RUUZQOiu15YBTaEjMqW_pfk1TguUrCRKNQPjhfvOtRk",
      "validationRecord": [
          "hostname": "erdos-labs.xyz",
          "port": "443",
          "addressesResolved": [
          "addressUsed": ""

Any ideas on how to get this up and running? Thanks a lot!