2a07-a880-4601-1402--2.pool6.ovpn.com IXFR zone transfer

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 2a07-a880-4601-1402--2.pool6.ovpn.com is not the root of its zone.
Instead, try zone transfer on pool6.ovpn.com .