A fatal issue occurred during the DNS lookup process for sohn.ix.tc/A.
DNS response for sohn.ix.tc/A did not have an acceptable response code: SERVFAIL
No valid A or AAAA records could be ultimately resolved for sohn.ix.tc. This means that Let's Encrypt would not be able to to connect to your domain to perform HTTP validation, since it would not know where to connect to.
No A or AAAA records found.