Restfull API meaning of http request error codes?

I’m trying to use the API on a local server and check for devices whether they’re alive. I’ve checked the status in the app: they’re alive but when i try:
Additionally I’ve tried: 

for a token that is online at the server an can be found by the app (so its really connected). And I get:

result: request failed, http Code: -5

I can’t find the http request error codes anywhere. So im rather clueless what is going on. Anyone got an idea?

That is the port for the App, not hardware… try 8080.

yup, got that from somewhere else as well. The result changed to: false. So its working BUT its says its not online, while the app does tell me that its online. Any clue?

edit: nvm: wrong token. It works. thnx