Hi there. Is there any chance to manually change the network operator like you can do this on our mobile phones? The problem is that I live in “black hole” of cellular network and i can reach only two providers. My antenna by default connects to the one that has a much weaker range. 
would be greatfull for any clues. Regards
You can only manually choose a network operator if the account linked to your SIM supports roaming. I.e. your operator supports intra-national roaming or you use a SIM from another country that has roaming agreements with both operators in question. These pre-requisites are the same on a mobile phone as well.
If you do have such a SIM, you have to set allow-roaming under /interface lte to yes to allow the modem to connect to another operator than the native one of the SIM.
Then, you have to run /interface lte scan lte1 for a while, to learn the names of the operators the modem can see “in the air”. And last, you set the operator value to the name of the operator you want to use.
If your SIM does not support roaming, you need to use a SIM from the other operator; in such case, no special settings on the LTE interface are necessary.
It works !! Thank You very much !
Best of luck.