rekordbox has no link

my rekordbox  has being working 100% for    1 year  .then last night i turn it on and bang no link.i turn off all my firewalls check all my cables.check my switch.what i use is this.one laptop toshiba satellite l750d one switch netgear 5 port gs605 ,2 cdj 2000 one djm 500. my cables are  cat 6.what could this be.all cdj are updated.rekordbox is  1.5.0