Constant buffering issue out of know where

I'm having lots of buffering issue regardless of show I watch or size of show could be 1GB or 10GB it will buffer very few seconds.

• Internet speed look fine even at the box itself. Tested and it's above 300mbps
• Uninstall Stremio completely clearing storage and cache. It didn't fix anything.
• Checked the addon version for torrent RD and it's the latest.
• I'm using ONN 4k with no other apps on it expect the one I can't uninstall.

4. I'm using realdebrid service

Anyone having issue any recommendations to troubleshoot the issue.