Why isn't it working? seriously? bandwidth is most likely not your issue Your compute power most likely is
real-time video encoding is VERY computationally demanding. And you are running 3 instances simultaneously. That requires you to learn to optimize both the operating system and OBS
Having a different base resolution vs stream output means you are having to re-scale the video, which adds to workload. Or maybe some of yoru OBS settings are a problem.
Regardless, I recommend monitoring hardware resource (CPU, GPU, RAM, Disk I/O, etc) utilization [for ex. using Task manager’s Performance tab and/or Resource Monitor] to see if your system is being maxed out with your settings, which is most likely what is happening. Not doing such monitoring is the equivalent of driving a car blind-folded and wondering why you run into things.