I installed Ubuntu 15.10 and the system wasn't automatically recognizing my Huawei E5776s-32 mobile broadband. After a few moments of tense Googling and a push to the right direction from here (in Finnish), here's what fixed it for me:
Type the following command:
$ dmesg
That's going to print out the kernel message buffer, and somewhere among it is your Huawei device's interface information. Look for the following line to resolve your wireless interface name:
[ 7.726156] huawei_cdc_ncm 1-2:1.1 wwx0c5b8f279a64: renamed from wwan0
I don't know why the renaming happens, if you do, please leave a comment! After resolving the name, activate and connect the interface to your computer:
$ sudo ifconfig wwx0c5b8f279a64 up
$ sudo dhclient wwx0c5b8f279a64
If you want to avoid doing this manually every time you startup, insert the commands in your /etc/rc.local file.