[ubuntu] Ubuntu looses track of 4G Modem after its been disconnected

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http://ubuntuforums.org – I have Ubuntu 12.04 and a 4G mobile broadband-modem called, ZTE mf880 ltf usb modem. Every time I loose internet-connection, Ubuntu seem to "loose track" of the modem and I have to pull it out and put it back in again, only to wait for Ubuntu to detect it again. This is quit irritating when I loose the internet-connection often. When I disconnect from the internet manually the modem works just fine, I can connect again without pulling it out and putting it back in. What should I do to get Ubuntu(network manager?) to always keep track of the modem, even after its lost its connectio (Hardware)