If you need to debug Kerberos, check the time synchronization at the first place. In about 50% cases it is it.
- the ntpd (or chrony) should be presented in the process list
- they should really be configured correctly
- in case of the virtual host crony is preferable, with the ntpd time skew is possible
Really nice crony/ntpd comparative chart: https://chrony.tuxfamily.org/comparison.html , “Summary” section is complete.