IP.get_local_interfaces() returns the above results
Also please don't mind the fact that I censored 127.0.0.1, I'm dumb
Also none of them are my actual public IP, idk what's going on
https://godotforums.org/discussion/comment/38992#Comment_38992
<-- referencing a similar question to yours.
Also... if you are willing or able to take a look at how to set this up in raw c; it may give you more insight into this process:
https://www.geeksforgeeks.org/udp-server-client-implementation-c/
Yea, after posting this I went and did some research myself, way harder than I initially thought
I haven't been ambitious enough to try what you're attempting now.
I AM tempted to try, though. I might try it after I finish the current project I'm working on.