More basic - is new computer running fine, when you don't start OBS Studio? if yes, then probably no problem with new computer.
You could return the new computer, but the chance is decent you'll make the same or similar configuration setup on a new/replacement computer and have a similar if not exact same issue
Alienware (Dell) has been known to use a 'Killer' network driver on some systems, which is known to NOT work all that well, and cause network problems (search this forum for examples, troubleshooting, and recommended solutions).. Is this your issue? i have no idea.
I'm guessing old computer was Win10, and new computer is Win11? or are you running Win10 on new 13th gen Intel CPU? Assuming new Win11 OS, and standard bloatware vendors install, there could easily be new background processes running causing an issue. These are easy to find/disable, if you know what you are doing.
Your comments indicate a non-sophisticated understanding of Windows Operating System. And troubleshooting is going to require understanding of the technology at both Operating System (OS) and application (OBS Studio, in this case).
My recommendation - find someone local who is knowledgeable about Windows OS and can show you some basic troubleshooting... and probably some Operating System config changes (I never run an OS with default settings... they suck). That person would also be able to see if you are overloading your new computer (CPU, GPU, RAM, Disk I/O, etc), check for unnecessary/inappropriate background apps/processes, OS settings, etc