Some users have reported that the phone while passing through areas without cell reception or poor connectivity switches to other bands. The revert back to 3G or 4G does not happen later when back in good-reception areas.
→ A temporary fix is to enable flight mode and then disable it. This can be done from settings or notifications.
I’m having a lot of trouble getting my SIM cards to access networks in the US other than 2G, and even then the phone is quite fussy. Has there been any updates to this recently? I bought my phone (GS290) a few months ago and had no problem in Europe (Switzerland/Germany), but have had poor luck trying to connect to US service (AT&T & T-Mobile). I’ve only gotten T-Mobile to work, and even then I can only get 2G coverage (EDGE). The phone never tries to access LTE. I’ve looked at the connecting to 3G/4G guides, and tried the flight mode trick to no avail. Calling customer service and tech support usually wastes 1 hour and only shows that I have a better understanding (which isn’t much) of what’s going on then tech support. Any advice appreciated!