Hello meljarabek

                               For network connectivity issue you need to check with the router by restarting or resetting by the router manufacturer assistance, because SB6190 is just a cable modem without Wi-Fi so if the modem gives intermittent connection issue please check using direct connection without router for confirmation and if modem cuts in and out you can try resetting modem by following steps mentioned on the below link

                               http://arris.force.com/consumers/articles/General_FAQs/SB6190-Factory-Reset

  Let us know if this helps.