A low-level connection error that isn't a clean HTTP failure, raised during bot startup or gateway connect.
TLS handshake failure, DNS resolution failure, or a proxy intercepting traffic to gateway.discord.gg.
Verify gateway.discord.gg and discord.com resolve and are reachable from the host. Disable or configure any corporate proxy or VPN that might intercept TLS. Retry; transient network issues self-heal on the next restart loop.