Probably didn't explain myself very well!
I have a static IP from my ISP which I can assign via a panel to blah.blah.com. What I need is a piece of kit that allows me to set it as hostname blah and domain name blah.com on the WAN side so I don't get mail server issues mostly. My present TD-W8980 doesn't allow this whereas the AG241 does.
Hope that's clearer