[FS#527] QMI modem Olivetti Techcenter (0b3c:c00a) freezes on uqmi --sync call (never connects)

[LEDE Bugs]

The following task has a new comment added:

FS#527 - QMI modem Olivetti Techcenter (0b3c:c00a) freezes on uqmi --sync call (never connects)
User who did this - Bruno Randolf (br1)

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I confirm this is a problem with TP-Link MA260 as well. uqmi --sync never returns. Uncommenting the sync call or adding the above mentioned workaround both work in this case.

Lede: 17.01.2 @ 97ebdf93a330ef1d7ff1cf6989cfb92ac2f5a386
Device: ar71xx Carambola2
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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=527#comment3490