It is a little hard to guess from the post, can we have the relevant section from the conf file.
My immediate thought however is that the second range has an issue with a netmask. It states that the subnet starts at 192.168.6.171 and uses a mask of /24 which would not end at 192.168.6.254
if this is the subnet you are after you would need a netmask to suit, now
i suck at working out netmasks so I wont embasses myself by giving you the wrong figure, there are calculators and the like about.