It was for that reason OpenVPN set up in SSL mode over TCP 443 was king, a few years ago most firewalls could not distinguish it from regular TLS encrypted web traffic. These days with application layer "next gen" firewalls though, a zealous network administrator can distinguish between the two and block just the VPN connection if they so choose.
Chinese V2Ray derivatives are indistinguishable from regular traffic and still penetrate the GFW but get detected when used for domestic services, which is not advised. Work best for short lived sessions in restrictive environments.
