ssh and potentially other services are failing with the following seen in syslog:
sshd: pam_access(sshd:account): access denied for user
The pam_access module is using the following file and the file is configured to only allow access for certain users.
Also, in /etc/pam.d/system-auth (or equivalent) this line can be found:
account required pam_access.so
To test this is the issue you are running into you can comment out the following lines in the associated pam configuration files and test:
#account required pam_access.so
You can also comment out the configured lines in: /etc/security/access.conf and test.
If the access.conf file is no longer required then leaving either the pam configs or the access.conf file commented out is a valid resolution.