Hi,
by the message, I guess you're looking for logread command. To check the logs head over to CLI, login and execute command logread which will output all system log that you're looking for. To find a specific message, like you said "Joined LTE network" you will need to use pipe function along with logread and grep commands command. E.g logread | grep "Joined LTE network" or logread | grep "LTE".
EB.
