Let's Encrypt & server security

Hi,
For security reasons we restrict access to ispconfig port only to certain ip addresses.
I assume lets encrypt authenticates the server by accessing port 8080. Do you know how we can overcome this? Maybe we can assign a different port with just access to lets encrypt scripts?
Does anyone have a list of ip's for the lets encrypt servers?

Thanks

 

Thanks. In this case I might have another problem. Will follow the tutorial again and update if necessary.

 

I am seeing this error on letsencrypt.log. Any ideas what is going wrong?

Error: urn:acme:error:unauthorized :: The client lacks sufficient authorization :: Error creating new authz :: Validations for new domains are disabled in the V1 API (https://community.letsencrypt.org/t/end-of-life-plan-for-acmev1/ 88430)