IMEI Number status is unknown AUXUS NOTE 5.5
According to my experiences, 

you just need the Region Rom for your Operator and Country and flash the Modem in your phone.and of course, if you have any backup of Efs, just restore or flash it.

also, try to download stock rom for your region and then test it.

hope this fixed. else, 

maybe you need the BoX for fix this.