similar problem with my vp540
I had a similar problem when i purchased my vp 6 years back, i noticed that sudden disconnection within versaworks when i was running jobs.
the problem was solved when we changed the ip range from the usual 192. etc etc it gets assigned with by the tech, down to 1.0.0.1, i first when into control panel on the pc, found the network card and took it off automatic and assigned the new ip address parameter, (just please check with your techs for the remainder of the settings)
then i went to the printer and changed its ip address too to fall within the range above eg: 1.0.0.3
Then re started versaworks and added the printer, problem was solved.
Funny enough i encountered another similar problem with my vp (the disconnection issue), (here in SA, we have very cold evenings and mornings during winter, temps around 5 degrees and lower), suddenly one day when we started using our vp for the first time in the winter months it suddenly disconnected, we couldn't get it to run more than 30%, we figured that as they day warmed up the problem stopped.
It went on for 3 days, then upon searching online for anyone else having a similar problem, we found a bloke from the UK was having similar issues, we deduced that the mother board was too cold and placed a small heater below the mother board area just to take the chill off and alas the problem stopped (we didnt hesitate to try and soon found that same solution also worked for us) till today Roland couldnt give me an explanation regarding the temp issue but yeah every winter it would fail until we warmed up the board.
so in conclusion it could be something with having its own dedicated ip range between a network card and printer, or something to do with temperature as someone else mentioned earlier in the thread.
But anyway good luck and keep updating us.