connectivity

I just had Spectrum Cable install a modem today with internet service (no cable, just internet).  I used my NetGear router to connect to their modem.  My Laptop and phone connect just fine using the wifi, BUT I can't connect my ROKU stick from my TV, or my XBOX wifi to the router...the connections are failing.  Any suggestions?  Also, i'm unable to login to the router (routerlogin.net & .com both won't come up).  Went to ipaddress using command prompt to backdoor login, but didn't work.  What's wrong??   Thanking you in advance!!