Are you over data limit, throttled? Are boxes at the top of page green when you go here:
http://192.168.0.1/ ?
Need to concentrate on getting things working first with computer plugged directly into modem before moving on to the S6 with router. Do not stream in HD simply because it will eat through your allowance regardless if it works well or not.
What is speed test result with computer plugged directly into modem?