I don't think proto 41 works like that. It's not like you open a connection, and this connection stays open and all data flows through it and the switches at your end will know where to send the data. No. Proto 41 needs end-to-end connectivity. How should the gateway know it is you that wants this package? You can monitor your interface with Wireshark to check for incoming proto 41 packages, but I think most 4G gateways will only work for TCP and - if you're lucky - UDP and ICMP.