This is a new router to our numerus WAN locations running IPsec. When the Cisco 2921 router would not establish an IPsec connection with our other sites we fell back to a 2851 router running adventerprise IOS which worked fine.
Is there a differance in how to configure IPsec with the Universal IOS than a advenerprise IOS? If so what?
You have not given us much information to work with here. While there may be some differences in configuration in 15.2(4) as compared to the code on your 2851 I am not aware of anything that would prevent IPSec from running, other than the possibility that your new router may not have the correct license to activate IPSec. If you are sure that the new router did have the correct licenses activated then I suggest that you provide some details of how the new router was configured and perhaps some debug output as the router was attempting to establish the IPSec connection.