How is your network setup since you have both a Netgear router and a 'modem'? Have you done the proper 'port forwarding' in your ADSL-router?
Perhaps your Netgear router is your ADSL-'modem' with 10.0.0.3 on the ADSL-line and 192.168.1.21 on the local network (howerver that one would usually be something like 192.168.1.1 = default gateway on your local network). 10.0.0.3 is a private IP address, which can't be accessed from the internet. Your ISP=Internet Service Provider must assign your router a public IP address which can be accessed from the internet. Contact your ISP to have it fixed. It is not uncommon on mobile networks to be assigned a private IP address.
73, Palle, OZ1RH.