Default [Q] Using LTE in Japan with european HTC One

Hey guys,

I moved to Japan for half a year and got myself a bmobile LTE data sim card for this time period. When I connected the first time after entering the apn settings for LTE provided by bmobile I had LTE signal and ultra fast Internet. Sometimes I just have LTE, but most of the time I am stuck with 3G and it's somewhat slower than back in Europe. So my phone is a german HTC One M7 and I am running Insertcoin 2.80 on it. Is there anything I can do to get constant LTE (Radio/Kernel/Firmware)? LTE is definately always avaible here in Nagoya, but they are using somewhat different channels than in Germany.

Thanks in Advance!