I have a Cisco 1721 router and have tried to install a VPN module MOD1700 - 3DES and a show diag indicates the module is not working. The module works fine in a 1720. I think I have loaded the correct IOS image c1700-k9o3sy7-mz.123-9.4.bin
I also tried c1700-k9o3sy7-mz.122-4.T5.bin - the same image as in the 1720.
The 1721 has 96 meg of RAM and 16 meg of flash, an SDSL WIC and an Ethernet WIC.
From what I have read the VPN module should work in a 1721, have I missed something?