You have not posted sufficient detail to advise upon (and you ignored the pinned post in this forum)
Are they the EXACT same make and model laptop? have you confirmed on the OBS PC via using Audicity on it, that the source connection is working well/as expected? [ie, confirm physical connection, and hardware and OS layer audio components... nothing to do with OBS
Assuming you positively confirm laptop is operating properly
- is the OBS laptop powerful enough for what you are asking it to do? what are doing for real-time hardware resource monitoring? if you aren't doing such, that is the equivalent of driving blind-folded
- then, are you use native OBS audio filters & effects? or 3rd party plugins? do you have adequate CPU and RAM for those effects?
etc