What would cause my BM38 server to think our public dns servers are

This was working fine yesterday, & starting sometime between 5pm mdt
last night & 8am mdt today, it says all 3 dns servers are down.

If I reload proxy, it thinks dns is up for a couple minutes, then down

The filter exceptions for outgoing dns are still in place, and stuff
like email & web traffic are still flowing through this server.

Even with filters unloaded, it still starts thinking they're down after
a bit.

What gives?