There is definitely a communications issue from your server to printer layer. The printing application you are using (Loftware) sends print streams/communicates via TCP/IP from your server to the physical printer. If you are unable to ping the printer when this issue occurs, there is a network or printer issue, not a specific application (Loftware) issue. No communications will be able to be established, Loftware or any other application.
This is also confirmed by your inability to access the printer via the printer’s web page. I would verify your network stability – there are a number of tools to do this. Secondly, (and easier) I would change the physical printer, if you have an extra one.
If the issue still exists, there is a very high probability it is your network (or maybe even a server/computer) issue. If the issue goes away with the new printer, it is a physical printer issue. If you are running multiple printers now, check to see if the issue exists on any other printers.