The configuration was correct according to sk33422.
I had reserved random IPs, and according to my support team I was instructed to reserve IPs at the beginning or end of the range, and replace the gategay address with *.
My setup looks like this and apparently it's working right now.
################################
### Gateway Type IP Address User Name ###
################################
* addr 172.16.0.254 user1
* addr 172.16.0.253 user2
* addr 172.16.0.252 user3
* addr 172.16.0.251 user4
* addr 172.16.0.250 user5
* addr 172.16.0.249 user6
Thank you all