Maintaining SSH configs can be a pain when you're hopping between multiple devices, even more when syncing apps (Synology/NextCloud/etc) are blocked on some networks/devices.
Make sure you have iCloud Drive enabled and this will symlink your SSH config + key to a folder in iCloud Drive and sync across devices.
The iCloud Drive is located at `~/Library/Mobile Documents/com~apple~CloudDocs`. By putting this file + your config/id_rsa files in here, it will simply symlink them. Warning - the setup script will overwrite existing config/id_rsa files.