From v18 and on, you should avoid ip addresses and non-qualified machine names to access the BIM Manager.
An example:
The computer you installed the BIM Manager on is : BIM-ManagerComputer
You used the default port: 1228
Your domain is: example.com
Then within the local area network and outside it you would use:
http://BIM-ManagerComputer.example.com:1228
Your browser and ArchiCAD will add the "http://" part so you can also type in simply:
BIM-ManagerComputer.example.com:1228
Your DNS server will redirect this name to the appropriate ip address.
If you use other methods there will be surprises, like missing libraries. I think you have bumped into those. Here is another you might see. Suppose in the above example somebody uses \\BIM-ManagerComputer:1228 (* note: the domain is not used only the machine name *) to share a project. Another person using an IP address will not see the libraries of that shared project. So the moral of the story is use a Fully Qualified Domain Name.
One other pointer: If you choose to use port 80, then in your browser you only need to type:
BIM-ManagerComputer.example.com
(For the http protocol port 80 is the default, so if you use it when setting up your BIM Manager, then it doesn't need to be supplied when you connect)
Hope this helps,
Ed
Graphisoft Technical Support