Hello everybody. Simonas was so kind to help me with configuration I was looking for few months.
I owe it to him to post his solution here, if anybody would have similar needs.
My setup is like this: I have ONE LAN in the range of 192.168.1.x. I have 2 SIM cards. I would like internet to be be acesed by SIM2 on my two TV's and for the rest of the network, SIM 1 should be used.
Here is how to configure this:
1. Network -> Interface -> edit MOB2S1A1 -> Advanced settings -> Set IP4table to 10
2. Network -> Routing -> Advanced Static Routes -> Add new instance of Routing table with TableID 10 and make route with interface LAN, Name: second, Target 192.168.1.0, IPV4-Netmask 255.255.255.0. Leave everything other blank. Add the route.
3. Network -> Routing -> Advanced Static Routes -> Add new routing rule for IPv4 as follows: Priority: 100, incoming interface: any, outgoing interface: none, Source subnet: 192.168.1.99/32 (the IP you want to be using SIM2), Matched traffic action: Lookup Table, Lookup table: second(10).
4. If you want you can add other IP's with adding more rules the same way (change just the IP) or you can use mask 28 or 29 instead of 32 (decide what range would suite you).
5. Save and reboot the router. It should work as expected.
Thank you again Simonas for logging into my router and helped me achieve that.
PS - You need to have the firmware RUTX_R_00.07.00