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 6li5j1jffjhplekvesonkc9kflu0ap1k.maxnet.org.pl is not the root of its zone.
Instead, try zone transfer on maxnet.org.pl .
Instead, try zone transfer on maxnet.org.pl .