Well, I’m using two different modems over Orange (Spain), a Huawei ME909-521 and I got 20/30 (and is a class 3!) and using a Quectel EP06 I got 50Mbps using two external MIMO antennas and configuring the Carrier aggregation using the AT command:
AT+QCFG=“band”,8d0,1a1880800d5,0
You can get more info here: https://www.ltehacks.com/viewtopic.php?f=15&t=674