Auto Setup failed authorisation DVNSI challenge on custom port?

Hi,
I’m trying to setup a cert for my server which is behind a firewall. The server is already running a service on https only on a custom port (no http access) with a self signed cert, so I wish to replace this with the let’s encrypt one.

running the auto command:
letsencrypt-auto --apache -d customport.server.com
I get the error:
`Failed authorization procedure. customport.server.com (tls-sni-01): urn:acme:error:connection :: The server could not connect to the client to verify the domain :: Failed to connect to host for DVSNI challenge

IMPORTANT NOTES:

  • The following errors were reported by the server:

    Domain: customport.server.com
    Type: urn:acme:error:connection
    Detail: Failed to connect to host for DVSNI challenge
    `
    Is this failing because I can’t specific a port for acme to query? or do I need a port 80 http access from the outside?

Regards
Damien.

When using the DVSNI method the server must be reachable on port 443. The Simple HTTP method can use port 80 or 443.