I'll give 4500 a whirl to see if it increases the success rate. It's a good idea. However it's not inconceivable to have sites like cafes that only allow 80/tcp and 443/tcp because that was an option in the UI on their wifi router for guest networks.
At this point if I was designing a VPN for client devices I'd have a mode that looked at as close to HTTPS as possible. There is one tool to tunnel over websocket but this was already sucking up too much of my play time. :)
Cisco AnyConnect, while expensive and bloated, works great as it initially connects on 443/tcp and then tries to setup UDP. If UDP fails it just sticks with the TCP connection and "just works".
At this point if I was designing a VPN for client devices I'd have a mode that looked at as close to HTTPS as possible. There is one tool to tunnel over websocket but this was already sucking up too much of my play time. :)
Cisco AnyConnect, while expensive and bloated, works great as it initially connects on 443/tcp and then tries to setup UDP. If UDP fails it just sticks with the TCP connection and "just works".