Huawei E1550 usb 3G slow transfer

Hi,
It seems like Mikrotik slows down the speed of 3G device at 1/1 mbps. Why?

HW used: RB3011UiAS,
RB: 3.35
RouterOS 6.38.5
Modem: Huawei E1550 detected as 0x140c ID (interface info says its E173)

Also this usb stick is not recognized as LTE device, only ppp-client is able to connect.

What should I do to get the normal speeds? This stick is supported by MT.