Cimplicity 8.2 server failure

my architecture based on cimplicity 8.2 sim 21 with redundant server concept.
its been working since last one year without having any issue
suddenly i got an issue where manual switch over its not taking place FROM secondary to primary
both PC name in gefredunancy.cim showing as secondary server name

let say my primary server name is STL0001
SECONDARY IS STL002

but in a screen its showing primary computer STL002 - SLAVE
secondary computer -STL002 - MASTER


cable redundancy enabled

P.S --> my LAN-B network used to break often