Running nw6.0.4 servers, one single time server getting time from an
internet time source. Rest of my servers (mix of 6.0.4 & 5.0.6a) are
secondary getting time from my single.

All was fine until this morning. One secondary server will not sync,
even tho it's on the same subnet as the single. The time offset is 0,
but it just won't sync up. I've tried turning off configured sources,
then back on, changing sources to <ip addy> then back to <ip addy>:123,
set timesync restart flag, timesync reset, nothing seems to work.

Any suggestions? I'm at a loss & need to get this fixed as we're
supposed to do a server migration this weekend.