I had a stable 3g and 4g connection for the first month. After one month it goes online and offline several times a day. It switches from 3g to 4g several times and it has been always located in the same place. When I reboot it I experience a good connection and after some time it goes offline. Sometimes the signal is poor and sometimes the signal is ok. I sometimes get "unknown error 80002"as well.
I guess you need more information. Just ask
Thank you :)