Hey Artem. First of all IP address on ground station side is dymamic but it does not change so often. If connection is dropped you can expect to get a new IP and you can setup IP on drone side before flight. From the other hand I own auto-connect modem with hot-spot option. I was looking for this modem for a long of time and now I can have LTE connection and WiFi hotspot at the same time. In this case I can access copter anytime if my mobile GS is in the range.
I agree with you that better option would be to have possibility to access to the PI pipeline without static IP form any other device. But Im little afraid that with 4G/LTE networks you wont find more effective solution that allow you to transfer so many data to end device in such sort time. Before this config I was using video cloud solution where latency was huge camparing UDP but cloud allowed me to access drone video feed from any devide.
If you are able to send pipeline as quickly as udp in different way please let me know. I agree with you that solution base on UDP is hard to be configured by end user out WF-FI range. I will have this problem probably If i deceide to migrate to huawei modem without Wi-Fi. \Right now its fine form me and I `m happy to have digital preview from copter