Sorry, hit return to fast.
Centos 7 joined to AD. After reboot, wbinfo reports domain as offline. Waiting some minutes or restarting winbind brings domain online. The unit-file for systemd has: After=network.target.
According to https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget/
network.target does not ensure fully working networking. Changing to After=network-online.target as recommended for clients resolved the problem.
Not reproducible on RHEL