First please read the https://wiki.mikrotik.com/wiki/Manual:Interface/LTE, part of r11e-lte6 cell lock.
Upgrade to v25 can work.
Probably to “fix” ca you can type:
/interface lte at-chat lte1 input=“at*call=0”
and below 10s the ca assign, check this.
You should could force B3 or B7 by Frequency lock like
/interface lte at-chat lte1 input=“at*call=1,3,earfcn”
where earfcn is a number of one of your B3 or B7 band center of freq ± width
In this mode you can lock band, but not tower and you can hop to other tower and his cell.
To lock tower&cell you must add phy-cellid
/interface lte at-chat lte1 input=“at*call=2,3,earfcn,phy-cellid”
.
You should add logs:
system logging add topics=lte
Enable LteLogger: http://forum.mikrotik.com/t/sxt-lte-4g-cat6/134468/1
and then you can track all stuff in logs.
You can do even a graph of max speed DL&UL from 24h at testmy.net .