Synology still supports (but does not feature update) DSM 7.1.1.
‘Method 2’ in the ‘Installing RoonServer on Synology with Docker’ sheet addresses Synology DSM 7.1 or older using the legacy Docker app.
I installed the legacy Docker app on my DS1515+ without issues.
The url shown to retrieve the image in ‘Method 2’ on the Docker install sheet returns ‘invalid’.
There is a ‘Docker image URL is invalid’ thread which has a solution but that solution involves going to the Project tab in the app and creating a new Project. The legacy Docker app has no Projects tab - I assume that solution is referring to the Container Manager app which is not available on DSM 7.1.1
The legacy Docker app does have a ‘Registry’ category which seems like it might apply. Where and what are the proper entries in the legacy Docker app to retrieve the roonserver:latest image?
(I do have a GitHub account if it is needed.)