Comment 1 for bug 1954877

Hello David and thanks for this bug report. Version 2:4.7.6+dfsg~ubuntu-0ubuntu2.26 had a regression with the Kerberos authentication, which is fixed in version 2:4.7.6+dfsg~ubuntu-0ubuntu2.27:

-------------------------------------------------------------------------
samba (2:4.7.6+dfsg~ubuntu-0ubuntu2.27) bionic-security; urgency=medium

  * SECURITY REGRESSION: Kerberos authentication on standalone server in
    MIT realm broken
    - debian/patches/bug14922.patch: fix MIT Realm regression in
      source3/auth/user_krb5.c.
-------------------------------------------------------------------------

Can you please try updating to this version and let us know if it fixes (or doesn't fix!) the issue you're facing? Thank you.