Help G3 purchased in Hong Kong...can i flash it so that I can use it with 4G service in the US?

[pengyou]

I bought an LG G3 in Hong Kong in May...then, unexpectedly, had to return to the US. I bought a sim card with an AT&T plan - one of the few that are supposed to work in North Dakota - only to find that it does not do internet very well, and barely gets 2G. Can I reflash this with a bios for North America and get more use out of it? I have bought another phone that uses one of Wal Mart's services (Verizon) but the phone, compared to the LG is a real piece...

 

[KOLIO]

Have you tried changing the APN settings ?

Here's what's listed for the AT&T LG G3:
(copy this exactly as posted)
http://forum.xda-developers.com/att-lg-g3/help/lg-g3-apns-t2820504

Name: ATT Nextgenphone
APN: nxtgenphone
Proxy: Not set
Port: Not set
Username: Not set
Password: Not set
MMSC: http://mmsc.mobile.att.net
MMS proxy: proxy.mobile.att.net
MMS port: 80
MCC: 310
MNC: 410
Authentication type: None
APN type: default,mms,supl,hipri,fota