Replica Status: Result toggles OK/Error…

I've got 3OD replicas, for my single OD all Server 10.5.6. One ODR same subnet as OD - Result remains "OK" Two ODRs in 2 dif geo locations - Result toggles between "OK" and " Error PasswordService - Not Found" Password Service Server Logs show users (geographically close to ODR) authenticating alright to the 2 wan ODRs, but the other day the OD had to go down, and the ODRs failed to authenticate users. I just need a punt in the right direction to determine where my issue lies. thanks for your time, d