1. Prioritising interfaces for general traffic is done by manipulating the routing metrics. Each route has associated parameters such as hop-counts and bandwidths. See netstat -nr and the "metric" option in the man-page for route command.

2. Prioritising application access to network resources is often addressed by "traffic shaping" - I'd use a web search-engine to see if Ubuntu or the router can do that.

1. Prioritising interfaces for general traffic is done by manipulating the routing metrics. Each route has associated parameters such as hop-counts and bandwidths. See the "metric" option in the man-page for route command.

    $ route -n
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref     Use Iface
    0.0.0.0         192.168.1.254   255.255.255.255 U     0      0        0 eth0
    192.168.1.0     0.0.0.0         255.255.255.0   U     256    0        0 eth0
   

2. Prioritising application access to network resources is often addressed by "traffic shaping" - I'd use a web search-engine to see if Ubuntu or the router can do that.

Footnote.

On MS Windows, but not on Linux, the netstat -nr command outputs the same information as route print. Including the routing metrics.