Just a weird problem we've noticed. I've been using the old trial (in fact I think we're at the last couple of days of it so a quick answer would be grateful) and, every now and again, it shows one of the internal servers being down with high packet loss (initially) followed by the node going down and an alert being sent of.
I've chucked the server that is running NPM8 on a GB port so it should have enough bandwidth to do all of it's pings but if it says XServer is down when I ping XServer it's replying quickly <1MS.
In the Node Manger open the Settings Tab and check the ICMP Timeout and packet size, make sure its set appropriately for your network environment, you might want to boost it up to allow for slower, or heavily used devices to respond. ICMP is very low in network priority. Also check in the Node Manager go to File> Advanced Settings> Node Warning Interval Tab, and make sure that it's not set to low.