Communication Error

Dear all,

I have 1 trouble, plz help me 

The last times, Client connect to 2 SEPM example A & B

so now, i change A to new server and power off B

and some client can connect to A, some client cannot connect to A

I already change sylink.xml, re-install SEP but not ok. ( the first times it ok but restart client, sylink auto change to old sylink )

sylink alway connect to B and A (new server)

Status: not connect

I use SymHelp and error about communication ( cannot find B )

I want to client only connect to A ( new server )

Plz give me solution.

Thanks so much.