The issue: The Teltonika RUTX11 shows 50-60% lower upload speeds while being able to match download speeds of the Huawei 5G CPE PRO (Balong 5000 modem).
ISP: Vodafone UK LTE bands 1 and 20.
Antenna: Poynting XPOL-2-5G V3 directional antenna pointing directly at the cell mast which is 820 meters away.
gsmctl -A AT+QCAINFO
+QCAINFO: "pcc",6300,50,"LTE BAND 20",1,316,-65,-7,-41,22
+QCAINFO: "scc",323,75,"LTE BAND 1",1,351,-86,-8,-69,23
Ping/Download/Upload results using speedtest.net when CA (4G+) is used and pcc and scc are in that order are:
22-28ms, 110-120Mbs, 16-19Mbs
If by a chance the order of pcc and scc is reversed, i.e LTE Band 1 (cell 351) becomes pcc and LTE Band 20 (cell 316) becomes scc then upload speed increases by 50-60% to 28-30Mbs.
I managed to confirm that by limiting bands in the modem settings to just Band 1 and getting consistent 28-30Mbs upload speed. Band 1 simply has a higher bandwidth 75 vs 50 on Band 20.
This confirms my theory that Teltonika RUTX11 currently uses PCC only for upload.
Now if I take that very same SIM card and connect the same Poynting antenna to the Huawei 5G CPE Pro I get the same download speed as on RUTX11 but 28-30Mbs upload speeds. The Huawei's specs clearly state that only one antenna is used as main and the other one is auxilary which is on par with RUX11. But somehow Huawei manages to get the best of both worlds - it uses CA and downloads on both bands (antennas?) but selects the best carrier (band) for upload.
Could you please clarify if this is a known issue? Is that a hardware or software limitation? Is that something that I could somehow address by explicitly specifying which CC (primary/secondary) to use for uploads? Or maybe it is something you could potentially fix in the next firmware update?