LG D505 no LTE after unlock

Dear Support

Have a D505, unlocked via octopus LG tool. Unlock successfull, but when I choose GSM/WCDMA/LTE setting in network mode, the unit does not find the network. Not 100% true the previous sentence. I experienced the unit catch the network after few min (not the LTE, only 3G), but after few min, the unit loose the network again. After that the software swich the unit to GSM/WCDMA mode, from that time the unit works well. The user want to use LTE network. Try to repair NVM, and repair security, IMEI repaired. Not help.

Any idea?