This question is an exact duplicate of:
I have seen a solution to a similar problem: Ubuntu hangs after replugging the modem
But what is the solution for a zte modem? I don't think it is the same as that of bcm_wimax. Help please.
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I have also experienced this problem.
The easiest solution for this is to plug in the ZTE modem to the PC/Laptop when it is off. Then start your PC/Laptop and it will not hang.
But if it again hangs after replugging then Restart your PC/Laptop and use the above method.
There is another solution you may try as explained in this thread, here -> Ubuntu hangs after replugging the modem