1 - Disable the modem's auto update, the update must be run when tcpdump is in listener
2 - Configure a linux to share the internet, configure the WAN port of the Huawei to receive the internet through linux with Fixed IP to facilitate.
3 - Install tcpdump on linux and run the command:
tcpdump -i $INTERFACE -w log.cap
$INTERFACE is the network card where the Huawei WAN was connected (ex: eth0).
4- Run update on Huawei.
5 - Stop tcpdump and Copy the log.cap file and open it in Wireshark, and filter by http protocol. It will show the htttp requests, and one of them will have the link used to get the binary.
6 - The ideal is to do the procedure only with the modem connected to the network, because a large number of requests makes the debug difficult.