I’ve run into this on two instances now, the second after I upgraded my RAM - since I thought that could be the issue. Followed the set up guide closely, and am running Ubuntu 18.04.
After setting up a new user, I went to http://[MY IP]/web-ui/login, and it my credentials did not work. On the second round, I ran again
docker stack ls which showed 9 services running. The same as when I ran it the first time in the tutorial. So, I followed the lines of code provided to docker:
docker stack rm syncldap
docker stack deploy -c /root/sync-endpoint-default-setup/docker-compose.yml syncldap
docker stack ls showed only 7 services. I repeated this a few times, and occasionally one item would fail to be created, but every time that result was repeated, with only 7 services and a non-functional web-ui/login.
I also tried disabling the firewall with
ufw disable, but this seemed to have no effect.