Getting this error and have looked at the other messages concerning it. I have tried reinstalling everything, 184.108.40.206 is not blocked, etc. The old Letsencrypt ran perfectly but have not had luck with it since going to CertBot.
Failed authorization procedure. allpingers.net (http-01): urn:acme:error:connection :: The server could not connect to the client to verify the domain :: Could not connect to http://allpingers.net/.well-known/acme-challenge"/PcdKLFD_fvWjEzt24gGMBo1_KfcVgtoxv7M1i1INM-s"