I installed Tomcat and Tomcat Manager on a remote server as per the instructions on this post.
After adding it I successfully accessed the manager on http://I
http://I
Just looked this up. Broken in Tomcat versions M19 and 8.5.13. Fixed in upcoming versions M20 and in 8.5.14. http://bz.apache.org/bugzilla/show_bug.cgi?id=60949. So you can roll back to M18 or 8.5.12 for now.