I am trying to replace a 2820 router with a new 2830 but having issues using the WAN Alias.

Current setup
BT 2wirehub (81.138.252.10) with two cables one plugged into my exchange server (all my mx records point to this IP)
other cable plugged into Vigor 2820n (81.138.252.12) all my VPN traffic, web traffic

New Setup
I want to replace the above setup with One ADSL Vogor 2830 using the WAN Alias My router will have 81.138.252.12 address
and 81.138.252.10 as a WAN Alias. I have opend a port from 81.138.252.10 port 25 and point this to my exchange

Issues
I have enabled ping from the internet and can ping both IP address's but when I test exchange connection i am unable
to telnet to 81.135.252.10 port 25

If anyone could help it would be very much apriciated.

Hi
Do you actually have a subnetted Address for example 81.138.252.10/29 so you have 6 using IP address?
If you only have the 1 static from BT then you wont be able to do it.

If you do then you need to create an open port rule or port forward to the interal address of the SMTP server from the Alias to the internal address