Hallo Maja
You have a sophisticated network - four network cards attached to one server(!) - but no clear idea what you are doing, or at least not communicated that here. You need to draw a network diagram and attach in your next post.
Here some random comments. But I don't think they will solve your problem:
> host name is currently showing "localhost.localdomain"
Of no use. It simply means the server can reach itself, which is always the case (in Unix). Except that it gives a bad feeling that you have installed the Debian with a GUI, which is a bad idea for a server.
> The Ip address is http://172.17.14.12/moodle
The IP address is 172.17.14.12, which is private. Good.
> And global IP is http://www.fiveto16.edu/moodle
This is not an IP address, rather a full URL belonging to the domain fiveto16.edu. Is this yet another example? Can't see it in the https://en.wikipedia.org/wiki/Domain_Name_System. If it is the one you want, you need to go to a https://en.wikipedia.org/wiki/Domain_Name_System#Domain_name_registration. If it is just an example, use example.com which is invented exactly for this purpuse; to use as an example.
> We have 4 eth0, eth1, eth2, eth3 card
See the beginning.
> Can this url help to sort this issue
> https://www.server-world.info/en/note?os=Debian_9&p=dns&f=1
No, unless you run your own DNS server, which is unlikely.
Installing and upgrading help
Reg local and Global IP
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