I would have just made the second interface on the 1841 my DMZ.
i.e. one arm of the router to the ISP
one arm to the DMZ
+ one arm to the LAN
You will need to allocate a separate subnet for the DMZ. If it's public access you may wish to use public addresses (supplied by your ISP) but if they are not available you can use private addresses and NAT the packets in.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...