So, are you doing basic monitoring of hardware resource (CPU, GPU, RAM, 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?
I suspect your PC is powerful enough, but OS issues could be hampering your efforts
You mention VPN - there is NOTHING you can do in OBS to fix upstream bandwidth problems, especially in parts of the world with ISPs blocking certain traffic, or poor upstream connections.
It appears you are sending your stream to streamlabs (I assume to re-stream?). Have you checked (this isn't an OBS thing) your sustained bandwidth to streamlab's host? Have you checked your upload bandwidth in general (not a speedtest, which is near worthless)? You need an equivalent of R1ch's TwitchTest tool to check your connection to the servers
https://r1ch.net/projects/twitchtest
You could upload a large file to Amazon, OneDrive, YouTube, etc and monitor sustained throughput to get a sense of your connection and ISP's upstream connection capability. Of course speed to 1 destination doesn't mean you'll get the same to a different destination
If you are using VPN - understand that probably isn't helping you as it is trying to compress already compressed traffic. if you have to use PVN, so be it, but then you need to troubleshoot the VPN software and service (not OBS related)
