Two internet connections available.
Two internet connections available.
Windows typically employs one or the other by default. The alternative usually remains inactive unless you're running an app that lets you select a specific NIC. OBS supports this, so it should function properly. Bonding is also feasible, though it can become quite involved.
There are many approaches to handling things. Prioritizing QoS to give the game the highest priority and Twitch-stream second, then placing everything else in a bulk category functions well. Personally, I use mobile-broadband as WAN2 and fiber as WAN1, allowing me to set up my pfSense device to direct all Twitch traffic through WAN2 while directing other traffic over WAN1.
Using a router such as pfSense offers excellent flexibility because you can manage traffic based on clients, IP addresses, ports, or any combination of these.
There are various approaches; with DSL you can obtain a Bonded Line, essentially two lines linked to a load balancing modem so they share the workload and effectively boost your upload/download speeds. You might also use an older method of Bridging connections to achieve similar outcomes (though I haven't successfully used one). Another option is purchasing a load balance router that supports multiple lines.
Bonding and aggregation serve distinct purposes. Bonding is the sole effective approach to significantly increase your speed, operating consistently across each frame. Simply linking two routers without proper balancing between connections won't enhance performance or improve load distribution. Your connection will still be limited to the maximum capacity of a single link.