Which version of OBS are you using? I face the same issue 1.5 years back on my Hosted OBS. I tried a couple of things which worked for me. Below are the steps that you can try.
Try lowering bitrate to 2500.
Don't stream over wireless, if you are.
Try another streaming service (Just as a test), like Xsplit and check if issue persists.
Update Network Adapter Driver
A Bad router or bad networking hardware can also cause he issue.
Regards,
Akshay