Simultaneous Lag Across 4 Servers? Same Host, Different Machines, Different Rack

[sharkaholic]

For the past two months, all four of my servers have been lagging at the exact same time. One of these has no plugins, nor is Oxide installed. The lag ranges from instant rubberbanding to crashing, and my host refuses to believe it’s something they can fix. I’m curious as to whether or not you guys may know what could cause this? All of the servers are on separate machines. The only correlation I can find is that when the lag hits, our CPU percentage across all four drops to 0.19%. Once again, it has nothing to do with plugins or with oxide, as one of them does not pertain Oxide Mod Manager at all and yet it still lags at the exact same time as those with it.
Any advice or ideas is appreciated, as I’m becoming fed up with empty servers. I didn’t spend the last two years building them up for them to fall down.
Shark-A-Holic