Wireless Joint

I have a Quectel EP06-A that will not keep up carrier aggregation on a second band. It is locked on Band 4 all the time but only intermittently aggregates Band 12. More often than not, it doesn't. Band 12 comes in just as well as Band 4 from the same tower, and the connection seems solid enough (see below). I'm not sure what's going on. Is it my modem/setup or maybe the tower? If it's on my end, is there anything I can tweak? (I've looked around but have not seen anything on point--hence posting here.)

Setup:

• Modem -> USB enclosure -> RaspberryPi 3b+ running ROOter
• Proxicast omni-directional paddle antennas
• T-Mobile unlimited plan of some kind
• ~2 miles near LOS to the tower (a few bushy tree branches from a single tree a few yards from the house)

Average connection stats:

• CSQ: 25-27
• Signal Strength: 80-87%
• RSSI: -59-63 dBm
• RSRQ: -7-8 dB
• RSRP: -88 dBm
• Speed is generally around 20 Mbps in both directions, somethings up to 30 Mbps down briefly

Any ideas?

Typicaly carrier aggregation only comes on under load. Not there All the time.
If you run a speed test and it come on during downlaod it is working. EP06 does not do upload CA