Hi all!
I have an RB751U running with 5.16 and a USB Huawei E353 which shows up, but has zero ports.
According to the wiki, this modem should be supported. Other USB modems, like the Ericsson MD300 shows up ok with ports.
It might be different hid/pid so here is what System/Resources/USB tells me:
Name: 0x1f01
Vendor id: 0x12d1
Device id: 0x1f01