Try nyo po mag lock ng dalawang band (either band 1 and 3, band 1 and 28, band 3 and 28 or any available band basta wag lang 40 and 41) using engineering mode sa naka mediatek at using rooted cp for snapdragon.
Engineer mode lods, may mkikita ka nkalist dun na "LTE ca configure" on mo ung switch tas airplane mode on/off then tada idk if working dko pa ksi natry haha kita ko lng