If I go ahead and use apt-get upgrades will it break the ispconfig3 setup? Do you have a tutorial for it?
it should be working. Alter the version name to strecth in /etc/apt/sources.list do the upgrade afterwards make ispconfig update and have it reconfigure service... HOWEVER: some people have reported a few issues - search the forum. Have a read at this and the following posts in that thread: https://www.howtoforge.com/community/threads/debian-9-with-ispconfig.76658/#post-361453
