I had the same issue using github.
Watch this:
Synology NAS - SSH access to console via QuickConnect using Docker
I followed these instructions (except I went with a full debian version):
Start Debian container
Enable SSH in Control Panel
double click Debian container select Terminal
In the terminal window
Enter:
ssh youruser@yoursynologyip
Enter your password
sudo -i
Enter your Password
docker pull ghcr.io/jgomez177/pluto-for-channels
type Exit
type Exit
close the Debian window
stop the Debian container
Disable SSH in Control Panel
Create a container for Pluto
There are I am sure other ways to do the same process - SSH into your Synology from a desktop SSH client such as Putty.








