Let me explain the subnetting.  On your router, you have a /27 subnet set up
for the Ethernet which is large enough for the router, the Max, and the 24
addresses in your pool.  But the router thinks all of those addresses will be
used on the Ethernet.  Instead of routing the packets to the Max, it does an
ARP request on the Ethernet.  Since the dialup customers aren't really on the
Ethernet, they don't see it.

There are two ways to make it work.  One is with Proxy ARP, which is how it
is set up here and probably on every other terminal serer you have.  The Max
sees the ARP request described above, and answers on behalf of the dialup
customer using the MAC address of the Max.  Then the router can deliver the
packet to the Max, which will then route it to the dialup user.  This isn't
really the way routing is supposed to work ... it's pretty lame, in fact.
But it works.  In fact most small ISPs tend to set it up this way because it
means they don't have to understand routing.

The other way is to actually route a block (or two) to the Max.  A static
route on the router for a /28 and a /29 will add up to 24 addresses.  Instead
of having your IP pools overlap your Ethernet, you would set up a smaller
subnet for your Ethernet (a /30 would work), and seperate blocks for your
pool.  When I set up a remote POP, I normally assign a /26, which gives me a
/28 for the Ethernet (allowing plenty of expansion or other devices on the
Ethernet) and 48 addresses for the modems in the Max.