I have a number of shared folders on a Synology drive which I can mount without any issues on a couple of different Macbooks running different versions of Mac OSX. I am assuming the folders are published using CIFS/SMB but I cannot mount them on my iPad using the file app browser. The iPad puts up a generic and not particularly helpful error dialog "There was a problem connecting to the server. Check the server name or IP address and then try again..."
I can connect to the Synology home page using a browser so network connectivity between it and the iPad is OK. Running "nmap -p139,445 --script smb-enum-shares " indicates that shares are up on both ports 139 and 445.