How to access cable modem status page 192.168.100.1

Question

How to access cable modem status page 192.168.100.1. It does not load behind the UTM but works fine when utm is replaced by simple asus router. 
 
 my internal local network is 192.168.0.0/16 
 
 i need access to the modem config page to troubleshoot signal issues.

darrellr · Answer

Since you would have a subnet overlap, I am not sure what the best way to access this would be. The UTM will not route the packet, and your workstation assumes the cable modem is in the same subnet, so it will not pass it to its own default gateway. 
 I believe you will need to drop your subnet down to a /18 or higher so you can rout through the UTM to the cable modem. You would set up a NAT address on the WAN port and then use it when connecting to the modem. Something like srcip (internal) to wanip (192.168.100.1) nat source as (192.168.100.10) or something to that effect.