Why does the ERR_SSL_PROTOCOL_ERROR keep popping up when opening websites with a VPN?

ISP FILTERS DISTORT THE TLS HANDSHAKE PACKET OR SYSTEM TIME HAS DESYNCHRONIZED.

Browsers stop page loading if a secure certificate is corrupted during transmission or deemed invalid. This happens due to DPI system interference in the encrypted channel or internal computer clock errors.

Causes of Cryptographic Handshake Failure

To load a page securely, your browser and the server exchange cryptographic keys. If DPI hardware attempts to selectively tamper with or filter fragments of the encrypted Client Hello packet, the browser detects a broken TLS structure and instantly terminates the session for security reasons.

How to Fix Protocol Errors

Check the accuracy of your device's system time and date with auto-synchronization enabled.
Clear SSL state in your browser's settings and OS network connections.
Switch to an alternative working tunneling protocol with TLS 1.3 support.
Temporarily disable built-in HTTPS traffic scanning in third-party antivirus software.