Cameras won't connect through browser

[Woody73 0]

I have four IP cameras and  I cannot see any of them through my web browser. I have them all connected to my router which is connected to my main router via ethernet. Could this be my problem that my router is connected to internet via the main router
and not direct to the internet.I get different errors depending what browser I try and use.
I have tried Firefox- Microsoft Edge- Chrome and Pale Moon and all come up with the same or different errors. The system is Windows 10x64. Also they are all connected and work with Blue Iris ver 5.
Thank you for any help.