In terminal server environment, losing connection to the internet from the client's local network, should not cause any data corruption. It will simply disconnect their session. I believe the data loss they're seeing is more due to the Delay Write Failed issue within the RDS server, and the Sage application server, and not due to them losing internet connectivity. I would concentrate on the former, rather than the latter problem, though, ultimately, both issues would have to be resolved, but IMHO, they're separate issues.