At first, update firmware lte module by:
https://wiki.mikrotik.com/wiki/Manual:Interface/LTE#Modem_firmware_upgrade
/interface lte firmware-upgrade lte1 upgrade=yes
Latest one is 026 but support have got a release candidate 027 and if you ask them probably they install it on your hw.
Second, enable LTE LOGs, to detect what happend when you have a “breake of internet”.
/system logging add topics=lte
Finaly, install the LTE Logger : http://forum.mikrotik.com/t/r11e-lte6-2ca-not-staying-connected/136004/22
With that info you can share your logs after reboot and wait 30minutes, good if your problem repeat. You can create a supout.rif and this is good point to send it to support@mikrotik.com too !
For us, you can just save logs to file by: /log print file=log.txt
Good Luck and give us feedback