After adding IP addresses to $FWDIR/conf/ipassignment.conf you can observe in smartlog that the IP addresses are beign assigned to other users. If you face with this problem, you have to use different networks for Officemode and ipassignment.conf. You can do it by subnetting the Officemode address pool or by using different networks.

Once you have different networks configured, if Antispoofing is enabled for Internet interface, you must to add the network used in $FWDIR/conf/ipassignment.conf to the exceptions for Antipoofing for that interface.