I’m curious if you are/were running docker on your NAS. If so, you might be able to run nzbget as a docker instance.
However I stumbled upon this thread because I’ve got nzbget running on my WD1400 and noticed it wasn’t supported in OS 5. I almost blindly upgraded from OS 3 to OS 5, and am thankful I checked first.
That being said docker was a native app like nzbget on OS 3, but I see no reference to it in the release notes as even being a supported app.
edited
Found others having issues with docker after upgrading to OS 5, and it appears to depend on the model you have. See OS 5 Roll-back - #4 by Czuz
