Cisco VPN with Anyconnect - What outside IP address to use?

Ok, this may seem like a silly connection but here goes.

I have a Site-to-site vpn set up between two of our offices.  The main and a branch.  For this site to site vpn I'm using our 'public' IP address that all the workstations get when they access the internet, (we use NAT).  The site-to-site works fine.

We also want to set up an anyconnect VPN.  It works internally using  I thought I could use one of our 5 external IP's (e.g. 70.x.x.19).  Is this the correct way of doing this?  I'm basically am confused on what IP address I shoud be using.  We have 5 address, 4 are used already for email server, web server and two other servers.

Any help would be appreciated!
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Henk van AchterbergConnect With a Mentor Sr. Technical ConsultantCommented:
well if that is the case you should look at the cable modem if you can NAT all ports to one inside IP address ( If that is not the case you should MAP port by port. At least HTTPS, 443, to

You should use the external 70.x.x.x IP for your clients to connect.
Henk van AchterbergSr. Technical ConsultantCommented:
You should use the "interface IP address" for anyconnect. You cannot use another IP address for terminating anyconnect on it.

If you have for example the outside interface with ip then you cannot use for anyconnect, you have to use
Jesh1975Author Commented:
Ok.  That is what I thought, but the problem is the outside IP is, which connects to our comcast business modem.

Then the cable modem is our public 70.xx.xx.xx.  

So I'm not sure what we are supposed to do here?
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Henk van AchterbergSr. Technical ConsultantCommented:
You say that you have several public IP's but your ASA has a private IP address? Why is that?
Jesh1975Author Commented:
Our setup is:

Inside->Firewall->Cable modem so all traffic hits the cable modem first, then is routed to the firewall, which has always been like this for this company.  I don't think we can make the cable modem 'transparent'.

Any ideas??
Jesh1975Author Commented:
Thank you this worked.  I still don't understand why my other public IP addresses (e.g. email, web server and so on) are working correctly.  They all work and do not have one to one mapping or anything.

Anyhow, I mapped our address to (ASA "outside") and it worked!  Next on the list is getting VPN clients to be able to access the network (the inside).

Thanks again for your help!
Jesh1975Author Commented:
Update: This ended up breaking our site-to-site VPN.  I forgot to update the comments on this.  I'm going to need to reopen this question...
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