Changes since SOA version
IXFR is a zone transfer request that returns changes since a specific SOA version. Enter the SOA version to request changes since then.
Not an apex domain
The domain ns4.avanzafibra-customers.es is not the root of its zone.
Instead, try zone transfer on avanzafibra-customers.es .
Instead, try zone transfer on avanzafibra-customers.es .