This could just be another device operating at 868MHz.
An IC880A receiving at 8 channels on every SF from 7 to 12 simultaneously will trigger more often than a RFM95 which listens at only 1 channel and 1 SF at the same time.
I see something similar. The crc_fail rate is about constant. messages with correct crc are variable.
my gateway on semtech
I suspect the crc_errors origin from my thermostatic device. I just wait until the summer. Then i will remove the batteries,
Art.