I went through all the settings and have made it work....almost. It works in the way that I want except for one small detail. To make the second modem work I need to go in to the settings for the "LAN2" interface and make a change to the DNS settings. If I just start the router the second LAN2 interface does not work. If I then go to the settings of that interface and either remove a DNS setting (for example 188.8.131.52) or if this setting is default (in my case 192.168.2.1) which is the router address for the subnet i chose, I then put in a DNS (184.108.40.206).
In summary. I need to make a change to the settings of the DNS to make it work. It doesn't matter if I put a DNS in or remove it. After the changes and save, it works but nerver immediately after power up.
What could be wrong?