I currently have Fiber Internet with near 1gbps Up/Down Speeds consistently and a 1ms Latency to the nearest speedtest server. using SLR I couldn't watch any video of any quality without getting constant buffering.
I tried many solutions and this is the one that fixed it for me, hopefully this works for you.
Without VPN:
Speed Test ID: 5430
86ms Latency 84Mbps Down 41Mbps Parallel
I recommend connecting to a VPN Server that is close to whatever city your speed test says the "CDN POP Location" is. Run your speed test here: https://cdn-vr.sexlikereal.com/benchmark/speed.html
I ran my test and it says Miami-2, USA.
I had already tried just a random VPN Server from Chicago and it was even worse buffering and streaming.
I connected to a Miami Server and my Buffering issues were gone and could stream full quality with no issues.
Connected to a Miami Based VPN:
Speed Test ID:5431
65.3ms Latency 99.1 Mbps Down 85.8Mbps Parallel
I recommend Paying for Cyberghost VPN however there are tons of other VPN options on the internet.
Hope this helps!