New
#11
OK I'm starting to get an idea of what's going on here. What I'm seeing is two different default IP's, this usually means that what you think is just a modem is actually a modem/router then it appears as if you are plugging that into another router with a different default gateway.
In order to confirm this I need to know the model number and name of the modem you are using, I also need the model number of the router you are using.
This is a very common problem and isn't so easily diagnosed, you would usually just need to turn off DHCP on the secondary router and plug the cable from the modem/router into the LAN port on the secondary router. Although there may be a bit more set up involved depending on a few different factors.