I replaced the modem on my LTE6 with an EM12-G and now have CA with b1, b3 and b28, my speed has increased to 120 Mbit/s down and 40 Mbit/s up. Well worth the upgrade.
Info here
https://www.uiblog.it/2021/05/quectel-em...-lte6-kit/
Multiple shops on AliExpress have the EM12-G modems
Info here
https://www.uiblog.it/2021/05/quectel-em...-lte6-kit/
Multiple shops on AliExpress have the EM12-G modems