getting my cameras thru the r6300 router

i tried to post this saturday but i was told to move it to a link provided and i went to that link and got no replies so i will give it a go again. if it is wrong sorry. 

some histroy first. i have a c3700 modem/router. and security cameras and with this unit i could see  my cameras at home and away for home. well then xfinity gave me more speed and then that modem could not give me that speed or even give me the speed i had before they changed it. so i tried a c7000 unit and that was slower and xfinity told me that, that unit was not compatible with my area's setup. so i had this r6300 router and with help from this site i got it hooked up to the c3700 modem and i got almost the speed xfinity was giving me now but!!!   

now the issue. i have security cameras and i did get them connected up to the router and they work great when i'm home. i can see them great on my tablet wifi connected to the router and the phone connected to the router.  BUT!  now when i'm gone i can not see them at all. so to test this close to home, i go next door and use there xfinity wifi and i can not see them yet. i have them all ported just like i did when i was just using the c3700 modem.router. so what am i doing wrong here? or is this just not going to work unless i  have a combo router and modem device?

i tired doing this once before to hook up this router and the c3700 combo unit and had a time even getting the router and the modem to connect, but with help from here i managed this time to get them connected up.  if this is not going to work i will just have to get a faster mode/router combo unit and just use on device. but before i just toss this setup out maybe all i need to do i click some switch and it will work. thanks