NetworkManager-wait-online timeout is too short
NetworkManager-wait-online will timeout after 30 seconds. We can easily see it take 40 seconds for a DHCP interface to be configured when connected to a non-portfast cisco switch. The DHCP timeout itself seems to be 45 seconds:
NetworkManager[1035]: [1566834776.1191] dhcp4 (eth0): activation: beginning transaction (timeout in 45 seconds)
so it seems that the wait-online timeout should be similar. This can cause services to fail because they start before the network is really up.