This error usually occurs due to problems with your internet connection, and there are many possible causes.
If you're using a VPN, it might be too slow or unstable.
It could be a problem with your firewall blocking connections or an issue with your browser's cache.
It could also be an ISP problem.
I recommend (if possible) that you try using another PC without a VPN. If the problem persists, then it could be a problem with your ISP or the hardware you're using for your internet connection.
If you don't have the same problem on the second PC, then something must be misconfigured on your PC.