I do not see how dial-up clients receive an IP address from the MultiAccess server.IP assignment via DHCP for the remote dial in users is not available in the MultiAccess.
Please reference pages 13&14 of the printed Quick Start guide that ships with the unit. The Web menu that address parameters given to the dial in users is "User Authentication" and then "RADIUS client".
The MultiAccess RADIUS client uses an IP pool method - for IP assignment to the remote clients.
The pool needs to be a consecutive range of IP addresses that do not conflict with your existing network.
Define the start of the pool range in the field "Remote Host Address" on the RADIUS Client page. The starting IP address needs to end with a (+) plus symbol (see step 11 on page 14 for more details).
The range of address numbers will automatically match the total number of modems/ports/T1channels in the MultiAccess.