Is there a way to disable 5GHz on the LWB5+
You can disable 5GHz on the SDIO version of the LWB5+, by modifying the NVRAM file (i.e. .txt file in /lib/firmware) as follows:
change devid=0x4418 to devid=0x4419
Note: This is currently not possible on the the USB version on the LWB5+ because the NVRAM information is included in the firmware.