In our office we have 2 separate computers that connect to 2 JBL Flip 4s each. We use the sync button on the JBL speakers to sync the 2. The 2 computers/speakers are separated by about 40 feet. Initially, the 2 speakers connect to their own computer as desired. However, after some time, all 4 speakers will link to 1 computer. How do I keep all 4 from syncing together?