The repository does not have a Release file

Hello Everybody,

Since I installed the LoRaServer on my VPS I get the following error:

Reason: 2017-11-18 23:22:06 INFO: pum is called with arguments: [’–list’, ‘–repo-info’, ‘–json’]
2017-11-18 23:22:15 ERROR: W:The repository ‘ xenial Release’ does not have a Release file., W:Data from such a repository can’t be authenticated and is therefore potentially dangerous to use., W:See apt-secure(8) manpage for repository creation and user configuration details., E:Failed to fetch 403 Forbidden, E:Some index files failed to download. They have been ignored, or old ones used instead.
2017-11-18 23:22:15 ERROR: Exited with returncode 1.

OS: ‪Ubuntu 16.04.3 LTS‬
Product: Plesk Onyx 17.5.3

Can anybody help me out?
Is it possible that I prompt the wrong APT repository during installation?

Thank you very much!

I think this is because of a misconfiguration. LoRa Server does not use a PPA repository. Please refer to the documentation, for example: