AD Domain join not possible

Hi Community,

I try to join a Sophos Firewall into our Windows domain but the domain join is not passible. I get this errors in /log/nasm.log:

Jul 26 11:59:18.983130Z ha.c:30 is_ad_join_required [nasm] is_ad_join_required() AD join required due to detected change in smb.conf
Jul 26 11:59:21.279112Z channel.c:178 __parent [nasm] connection closed, verify baby's health :)
dos charset 'CP850' unavailable - using ASCII
kinit succeeded but ads_sasl_spnego_gensec_bind(KRB5) failed for ldap/dc.dom.local with user[sophossso1] realm[DOM.LOCAL]: Invalid credentials
Failed to join domain: failed to connect to AD: Invalid credentials
Jul 26 11:59:22.001602Z channel.c:517 net_ads_join [nasm] '/oss/net' exited with invalid status '255'
Jul 26 11:59:22.001702Z channel.c:1253 pre_channel [nasm] net_ads_join failed to join with server->DOM

If I test my LDAPS connection (only encrypted connections allowed) to the DC, it works well. It is also possible to browse throught the AD with the "Import Group Wizard"

Ben