We currently try to strengthen our router configuration and I hoped that some experts can take a look to our current configuration I did as recommended by some literature I found.

Perhaps you can tell me what can be improved, needs to be added or even can lead into serious malfunctions of our network.

Our network topology: Cisco 1712 router (the one in question) connects via symmetric DSL using static IPs).

Behind the router our WLAN resides (uses one static IP) as well as two servers (one IP per server).

Each of them runs web (http, https), e-mail (pop3,smtp,imap), web mail, ftp and dns services (one primary, one secondary with ability to allow zone transfers to a specific outside backup dns server).

I look forward to your insights. Please, when giving advise, be generous and explain step by step what I need to modify (I work with SDM to configure the router, so haven't much experience with the command line interface).