Yes, but IPv6 helps a ton. Hole punching with IPv6 is almost 100% successful as long as your firewall allows it (and most do unless you are whitelist-only). IPv

Yes, but IPv6 helps a ton. Hole punching with IPv6 is almost 100% successful as long as your firewall allows it (and most do unless you are whitelist-only). IPv6 kills symmetric NAT and over-provisioned NAT.