Starting on Sunday, our network started reporting a handful of servers and devices dropping network connectivity, then coming back up, and all at the same time. We have a SQL server, two servers for Solarwinds Orion, and a couple other devices that are having the issues. Using the SQL server as an example, when it drops, I am unable to ping the default gateway, which is a Sonicwall NSA 2400, or outside to the internet. This happens with either the primary or secondary Sonicwall. Internally, our terminal server can connect to the SQL server without any issues, and our Exchange server has had no issues. I can connect to it no problem from my desk as well, but other users in the building cannot connect directly to the SQL server. The general manager can, at his desk, ping it by its DNS name, but cannot ping the IP address itself. (Yes I said that right, it will respond with the DNS name, but not IP address). Other users cannot ping either. I have checked all of the servers for potential viruses, all came back clean. I have rebooted the switch, both Sonicwalls, the DHCP server and the DNS servers. Cleared ARP cashes and flushed DNs on the servers. The servers connect to a Cisco 2930 switch, and from the switch to the Sonicwall. And this happens with both LAN and DMZ connections. There have been NO changes done over the weekend that could be the culprit. Any thoughts?