I got my phone from Korea the s7 edge. I am only getting the 3G instead of LTE. I have tried changing the APN settings but as soon as I save the settings, it disappears and looses all connection. Is there any ways to get lte ?
Welcome to the community!
Do you know which version of the S7 Edge you have? There are (at least) three versions from Korea: SM-G935K, SM-G935S, and SM-G935L. Judging by the specifications provide by Frequency Check, Both the K and S versions should have all of the compatible bands/frequencies for LTE.
That website does not list specifications for the L version. However, if we use the S6 Edge L version specifcations as a basis, it's possible the S7 Edge L version only has two of the compatible bands/frequencies, bands 7 and 17 (2600 and 700bc MHz, respectively). You can verify the compatible bands/frequencies here. While the phone should work on the LTE network, coverage depends on the bands/frequencies of the surrounding towers. You can get an idea if the towers in your surrounding area here.
(All of those versions would only have one compatible band/frequency for 2G (band 2, 1900MHz) and both compatible bands/frequencies for '3G'.)
Have you verified you have a LTE-capable SIM? Have you tried your SIM in a different phone or a different LTE SIM in your phone?
Since the phone is LTE-capable, it should be using ltemobile.apn. You can verify the correct settings here. What APN is currently listed? After you tried to change the APN settings and save them, did you restart your phone? Have you tried to delete the current SIM and creating a new ltemobile.apn? When you said '...it dissapears and looses all connection...' do you lose '3G' or 2G as well?
Have you enabled roaming and roaming data? Some phones from abroad think they are roaming when they are out of their expected areas even though they might be using a local SIM.
Have you verified the network mode on your phone is set to LTE/WCDMA/GSM auto? You may have to do so using codes, as this community user did here. Your particular phone may or may not have its own set of codes so you might search for the codes specific to your phone or manufacturer.
Hope this helps